odd work truck...

[cracker0169]

Well, we have a weird setup on a work truck where I work at. Its a 1990 Chevy K30 (new body style) cab and chasis that we have a box setup on. The truck is set up as a contact/welding truck. I climbed in it the other day to drive and was blown away when I grabbed a hold of the shifter. It had the signature L-1-2-3-R of a SM465. Has anyone ever seen a sm465 in a 1990 NEW BODY STYLE Chevy truck? It hasnt been converted or anything else, this is all GM. The boot, plate and everything else in the floorboard is all factory. It just blew my mind...


Anyways, I'm glad its FRIDAY!!!

[VileZambonie]

They came factory with a muncie 4 speed M20

[cracker0169]

I thought a m20 was an old school trans that came in muscle cars. I havent climbed under it to look at it yet to verify though. I do know that L (what I call first) and R are not synchronized.

[Blazin]

I looked at a 89 extra cab 1 ton 4x4 last fall. It had L-1-2-3 as well. It looked like an SM 456, NP 241 combo to me when I peaked under it. The guy was the original owner and insisted that it had never been swapped.

[VileZambonie]

That would also have been the muncie 4 speed. same trans

[HAULIN IT]

Cracker, The transmissions your thinking of are the Muncie M-21 (wide spread ratio) & M-22 (close ratio).  220,221 What ever it takes.

[zieg85]

M20 wide ratio either 2.52 or 2.56:1 first gear
M21 close ratio 2.20:1 first gear
M22 close ratio 2.20:1 first gear

all available in GM from 63-74

http://www.yearone.com/updatedsinglepages/Id_info/muncie.htm

[HAULIN IT]

Opps! Sorry! Good thing this isn't a muscle car site, you could likely get burned at the stake (or key board) for an error like that. I had allways heard the M-22  had "less split" than the M-21, just never knew about or forgot about the M-20. Go figure on the "extra close", keep us in line Zieg! Vile, the tranny your referring to, I'm guessing is a "truck type" top shifter & not related to this family of trannys, correct? It just happens to carry the same M-20 identification?  Lorne   

[zieg85]

Upon further digging they show an RPO  M20 listing a Muncie 4 speed for the years of 76-88

[VileZambonie]

Up until 91 it is a muncie 4 speed 117mm trans for the 4 speed application.

[cracker0169]

well, I guess its not a 465 after all... thanks guys...

[zieg85]

well, I guess its not a 465 after all... thanks guys...

Well... here is a link that we all might learn from, at least I did

http://www.novak-adapt.com/knowledge/sm465.htm

[1976Scottsdale]

well, I guess its not a 465 after all... thanks guys...

Yes it most likely is, just with an aluminum top plate instead of iron.  A Common error around my parts is people seeing the SM and thinking Saginaw, when it is a muncie.  Granted I have torn down Saginaws and Muncie's and there isn't a really great deal of difference... aside from that signature "rock crusher" tooth pattern.

[Captkaos]

The RPO M20 is a SM465 in 3/4T-1T trucks from 1973- 1991 in both bodystyles.  It was used until 1992 when it was replaced with the NV4500.

[cracker0169]

just leave it to the cop-i-ton