HD Muncie 3 speed (RPO MC1)
 

My 77 2wd C10 with the 350 engine was ordered with RPO code MC1, which is labeled on the service parts i.d. sticker as a heavy duty 3 speed Muncie. It's my understanding that this was an upgrade to the standard light duty 3 speed tranny.

I'm trying to order an output seal (where the driveshaft yoke slips in) and no mention is made of this transmission for this specific part. Anyone have any info? The Timken 9613s seal is listed as fitting the "3 speed manual Tremec, the 4 speed Muncie 27 spline, and the M15 3 speed." Is this the correct part #?

Re: HD Muncie 3 speed (RPO MC1)
 

Anyone?

Re: HD Muncie 3 speed (RPO MC1)
 

I don’t if your part number is right but these guys might help.

http://www.garagemotorsports.com/muncie.htm

Re: HD Muncie 3 speed (RPO MC1)
 

GM used three 3-speed transmissions in the trucks. The parts books illustrations should allow you to ID which one you have...

According to the parts books MC1 is a Tremac 3 speed manual transmission.
Tremac is the way it's spelled in the parts books. Not to be confused with the FORD Tremec...
http://www.gmpartswiki.com/getbigpage?pageid=60878

This is the MC1 Tremac 3 speed... It looks like the MC1 should be hours or even days of entertainment to service if it comes to that. On par with the HM290 or 5LM60.
Note the shift rails and the lack of a side plate to service the shift forks.
http://www.gmpartswiki.com/getbigpage?pageid=55541

This is the Saginaw 3 speed illustration.
http://www.gmpartswiki.com/getbigpage?pageid=55550

This is the Muncie 3 speed illustration. Note the additional lug on the shift fork plate.
http://www.gmpartswiki.com/getbigpage?pageid=55555

Re: HD Muncie 3 speed (RPO MC1)
 

So is that Tremac a "toploader"?

It would have been the base three speed in Pontiac GTOs as well (if that's the case).

K

Re: HD Muncie 3 speed (RPO MC1)
 

It depends on how you define toploader.

I thought that meant the shifter and forks went through an access plate on the top of the transmission.

If it means the gears are loaded through the top when it's being assembled then it's a toploader... with a side mounted shifter.