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gfhngngngh

i have an SM465 too, but haven't seen too many others


1970 GMC Jimmy 502HO/SM465/NP205 doesn't run just yet!

Yep me too! I think they are around if you need one. My father-inlaw has one in his 72 K10PickUp.Early 70s Chevy 4x4 that is the manual of chioce.Awsome!

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The factory did make a lot of Blazers (relatively speaking, that is) with the 4-speed. I think it's something like 35 percent were 4-speeds, with the remaining 65 precent either a TH350 or a 3-speed (don't know the percentages, just guessing here). When I was looking for a Blazer, all I could find were TH350 models or 4-speeds that were converted to autos. I found one Jimmy that was an automatic converted to a 4-speed (it was a hack job and had horribly high pedal effort). I looked for over 2 years before I could find a reasonably solid 4-speed truck (and I live in California!).

I've got the 465 4-speed/205 combo in my 72 with 3.07 gears too. That low first gear is the only thing that makes the axle ratio tolerable.
Kelly

I bought mine with a TH350, it is now a 4 spd. Im still restoring it, haven't driven it yet. I did appreciate the low 1st gear in my last truck when I was pullin the boat out of the water.
Jeff

I looked high and low until I found a gmc with a Muncie Rockcrusher. My C/10 pickup has this type tranny and it rocks! I tried a th350 in my (late lamented) K/10 sub, but it sucked in the hills or offroad -- it would not stay in gear but pop into high on its own. Give me something I can control.
I seem to remember that Chevy was pushing the automatics hard in those days, you had to special order a 4-speed and that costs extra and (the guy in white loafers said) "it lowers the resale value(!?) besides this way the little woman can drive it too."
I guess GMC had more latitude in their options selectable. Either that or they got to use up the parts the Chevy Division was making obsolete.

My 72CST is factory 350, 4sp, np205, and 3.07 posi. I dont
use first unless im pulling something.

72CSTK5

The "Rock Crusher" name was tagged to the M22 Muncie car transmission... It was a close-ratio transmission with a 20 degree helix cut on the first three gears. It sounded kind of like it was grinding rocks as you drove down the road. I believe that it was Brock Yates that coined the name when test driving a Corvette for Car and Driver. The M20 and M21 Muncies had more helix angle on their gears and made less noise but also had a slightly lower torque capacity because of it.

mine has 4 speed with 373's locked

I stand corrected. I thought it was a "Rockcrusher" because of the durability of the cast iron casing especially if you high center it on a rock. [Easier to do in a C/10 than a K/5]
BTW is the 4x4 unit different than the 2wd? I know I had to get a wider hole bellhousing when I was putting a 350 crate mill into my jimmy.

The case should be the same on a 2WD 465 vs. a 4WD 465. I have seen a few 2WD 465s in J-yards and the top cover and case appear to be the same. The bellhousings on the ones I've seen were exactly like my original cast iron bellhousing. The only difference I could see was the tailstock and output shaft.

Can you elaborate on the difference in bellhousings when you changed to a crate engine? When I got my Blazer, it had its original 465 in it and a Goodwrench crate engine, and the bellhousing fit fine (of course, now it has neither the original tranny nor the Goodwrench 350...).

Actually the Bellhousing with a smaller hole came off a J-yard 465 that I got some years ago to R&R trans in my C/10. When I was prepping for the K/5 engine install I thought I'd use it since it was already loose, rather than screw with the one that came on the 327 that was on the Jimmy when I bought it. [Obviously not the original engine, it sucked valves #6 and 7 when me and my buddy tried to jet down a 790CFM Holley doublepumper to pass emissions--it blew out on the way there, I limped home and the rig sat for a long time until I could get to it.] Anyway after I got it magnafluxed, beadblasted and painted Chevy Engine Orange, I noticed its internal diameter was smaller than the one on the truck. So I used the other one.
I wonder what it's off of?
BTW how come a Jimmy is a K/1500, just like a 1/2 ton pickup, whereas a Blazer is a K/5 and a 1/2 ton is a K/10. Shouldn't a Jimmy be a K/750? This conundrum keeps me up at night. LOL.

OK its not one of the first gen K5's but my 81 Jimmy was a 4 speed truck from the factory, and it had all the power options and A/C. I have looked at literally hundreds of these truck (all second gen) and every one I see with the 4 speed is ex-government (like forestry) base model, no options. I have yet to see another fully decked out K5 with the SM 465. I know they're out there I just haven't seen another. How rare is this? Don't get me wrong, its just a curiousity thing, I hate the power options and the A/C has been dead and gone for quite some time. When I saw this truck originally I thought, I gotta have it, I love the 4 speed and you don't see it in K5's so much.http://www.coloradok5.com/forums/images/icons/cool.gif

I have been told that the 2WD version of the SM 465 is a lousy candidate for swapping because of the tailshaft swap that needs to be done to use in a 4WD application...never looked at it too closely though. The 4WD versions are a dime a dozen so it never seemed to be an issue worth finding out more about.


Rene

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Opposite in IL, 4wd version of any tranny is hard to find, the 465 are a dime a dozen(2wd).

68-79 4x4 465 used 10 spline output shaft(easily adaptable).
68-88 2wd used 35 spline output shaft.
80-88 4x4 used long 32 spline output shaft.
This tranny was used 68-88 and the case housing never changed.

465 were only optionally available, as were the TH trannies.
3speed manual was the standard equipment trans.

Yes, 350 engines and Auto trans was used the most, in 71 and 72 .....
467,968 350 engines were sold, and 413,834 auto trannies were sold.
142,645 CST packages were sold, and over 800,000 units were built for 72.

Enough info for now, laterzzz....


'72 K-5 4x4, CST, 3.07, 4 speed, NP 205, 31' x 10.5", Olive green and primer, rusted out, rice smasher!<P ID="edit"><FONT SIZE=-1>Edited by R72K5 on 03/18/01 04:44 PM (server time).</FONT></P>

Very wierd on that bellhousing. When I broke the bellhousing on my original 465, I used one from a '69 2WD pickup. It fit just fine. I'm sitting here wondering if the bellhousing you got wasn't off of a different tranny (Rockwell, Saginaw), as I don't think that they ever changed the diameter of the input shaft bearing and retainer.

I'm sure it was attached to a 465 from Millie's Salvage (Tucson) that I put in the orange pickup, back in the mid 80's. I used my original bellhousing, so it was kicking around the parts shed until the Jimmy project came up. Poor sad bellhousing. It had its chance. Now its all dressed up and no place to go. :(
I also have the old Muncie M20 that came out of the [c/10] pickup -- synchros were shot-- is it a different unit from the "K/750" as far as tailshafts are concerned?
I kept the core instead of collecting my $15 core charge. Is it possible to get a rebuild kit to R&R synchros and bearings? How big a hassle is this?

Hmmm... I don't know what the differences would b from an M20 to a K/750 (don't know what a K/750 is). WRT the rebuild kits and synchros, the Muncie M20 family was quite popular and rebuild kits, snchronizers, and blocking rings are still available as service replacement parts. Check with National Drivetrain or Discount Parts Wholesalers.

I have a 1970 K5 that came stock with a 350 and a NP465 4 speed and a Dana 20 transfer case. I have 3.73 gears in the diffs. for the hills in Utah the combo is great. However it's wound pretty tight on the freeway.

I will try and get interior diameter on bellhousing in question. The machine shop guy offered to open it up to the larger diameter, but I decided the production one was better stressed for it.
"K/750" is my little joke. If a K/10 Chevy is a 1/2 ton pickup, and a Blazer is a K/5 -- So if GMC 1/2 ton is a K/1500, therefore a Jimmy must be a "K/750." Right? I mean it makes mathematical sense, but the marketing people had their own reasons why its really called a K/1500 Jimmy. Go figure?! Probably it sounded too much like a motorcycle number.
LOL

I'll have to agree with Steve C. i bought his smelly :-) 465 and along with it came the housing. I thought i'd use it as a reference. but i had bought a housing from a 2wd at a jyard. Actually i compared several housings that were mated to the 465s and did not notice any diffences in them.
i did notice there were different casting numbers but everything else matched. I could not find any differnces, once convinced that there was no diff I threw the broken housing away.

ARQ.

I looked at my mystery bellhousing and came up with the following data:
Interior diameter: 4 3/4"
casting numbers as follows:
(GM11)on left (3815891) on right of hole.

<blockquote><font size=1>In reply to:</font><hr>

I have a 1970 K5 that came stock with a 350 and a NP465 4 speed and a Dana 20 transfer case.
I have 3.73 gears in the diffs

<hr></blockquote>


[b]reedthis[/b, the Blazers with 350 engine were equipped with 3.07 axles, and NP205 case, the only Blazers that got the Dana20 case were the 250 equipped Blazers, and the Blazers with the 250 and 307 engines were equipped with 3.73 axles, unless 3.07 was specifically ordered.
Either soemone installed the Dana case, or it was a 250 Blazer, originally, which makes sense because of the 3.73 axles, hehe.....]

GMC K-750 sounds right to me, I like it !

The Muncie M20 were passenger car transmissions, save it, even if it needs rebuilt, the cases and mainshafts alone, are worth $$$$$..
Unless you mean option # M20, which is the GM RPO code for the 4 speed truck manual tranny (CH-465 in '69-'72 trucks)
The CH 465('68-up) is built by Muncie,
and the SM-420(through '67) were GM/Saginaw..

A passenger car manual transmission can never go into a 4x4....


(I hope I didnt misread something you typed out)






'72 K-5 4x4, CST, 3.07, 4 speed, NP 205, 31' x 10.5", Olive green and primer, rusted out, rice smasher!

I have a 72 Blazer with a SM465 and 3.73's in the pumpkins. If this is not stock one of the previous three owners was messin' around with it. Actually, I know that someone has been messing around with it: Holley carbs from the factory, I don't think so!!!

I am running 33's right now (without making any sort of adapations for my speedo - which is a little out of whack). I am finding that I have to shift at 12 mph, and 25-30mph according to my wonky speedo. Does this sound right to you? I feel like I can hardly get the thing moving before I have to change gears. Could it just be my worn out engine?

Thanks,

Rod

http://72blazerod.coloradok5.com

"A passenger car manual transmission can never go into a 4x4..."

For the most part this is true, but Richmond Gear has a GM 4x4 version of their "Street 5-Speed," P/N 7021703-A... I don't think I'd want to run that close a set of ratios in a truck, but they do offer it (along with a GM Truck version of their Road Race 5-speed).

Hehe, wasnt expecting Richmond to get thrown in, lol

Interesting tranny that is.

'72 K-5 4x4, CST, 3.07, 4 speed, NP 205, 31' x 10.5", Olive green and primer, rusted out, rice smasher!

i have a 72 jimmy with a 350 and a 4 speed. i dont think the gears are 307 though. it feels lower than that to me, tachs up pretty good a 70mph.

Well, on the Blazers, 3.07 gears were included, when the 350 engine was ordered..... it is option code LS9, and will be on the glovebox door, if the truck is an original 350 equipped truck... Maybe GMC was different, dunno........ GMC was odd on a lot of things...
Good luck

'72 K-5 4x4, CST, 3.07, 4 speed, NP 205, 31' x 10.5", Olive green and primer, rusted out, rice smasher!

I was looking in my barn for parts, to put a 465 in my Jimmy. I came across a bellhousing with the smaller hole for the imput shaft bearing retainer. It came out of a 66 Impala, with a four speed Saginaw.

When I rebuild my '68 C/10 Stepside as a near future project , I may be able to absorb that bellhousing. It's already painted.

Randy, the Dana 20 t-case thing is not as simple as you think. I have been hanging around on the 1st gen. Blazer board for a few years, and there have been many people with stock Blazers with 350s and Dana 20s. They may all be with manual transmissions (Saginaw 3 speeds or SM465s). I am pretty sure that there are a few TH350 automatics with Dana 20s floating around out there too.

Tim

70 Blazer CST 4X4 350 SM465 NP205
87 Burb 4X4 350
01 GMC 2500HD 4X4 Duramax/Allison