The Stovebolt Site Forums The Shop Area Driveline tranny swap - Muncie 4spd to 3 on tree for 1960 longbox C10

Hey all, been a while but I've still been tinkering with my 1960 longbox C10. Anyway I have a few questions on a tranny swap. First off my truck currently has the Muncie 4spd (Granny Low) and I would like to put in a 3spd "on the tree" colum with a 3spd OD tranny. So I know that the 2 trannys are different lengths so what exactly would I have to modify to get the 3spd to bolt into where the 4spd was? A new tranny mount? Do I have to change the driveshaft? (I know I will have to get it cut but I have the 2 piece shaft with the hanger bearing, do I need to get just a onepiece shaft from a longbox truck originally installed with a 3spd??) Will the linkages and steering colum bolt up and clear all the body and frame openings in my 4spd truck? If anyone has any info,tips,or other comments please feel free to say I like to get all the info I can!

THANKS ALL!
-Danny

Why would you want to change to the 3 speed from a 4 speed?
If you want an OD transmission go for at least a floor shifted one, then you can stay away from the troublesome column shifter and linkage. How about a T5?
Another option may be a faster rear axle gear and keep the 4 speed you have now, you can probably get the same overall results you are looking for.

If you must swap to the 3 on the tree then it sounds like you know what to look for, and what the issues may be, I bet you figure it out as you go. You will most likely end up in a junk yard puling all the goodies you need from a 3 speed equipped truck, seeing one together and having the parts available should answer a few more of your questions.

Good luck,
Grigg

IIRC, if it's a granny low, it's not a muncie, it's a saginaw.

Regardless, I would say that your odds of connecting this should be very high. If you don't have slop problems now when shifting on the column, none should be introduced by this transmission. I'm going to assume that you have the 3spd OD (6 spd really) with the electronics; in that assumption I have seen a very good video of someone doing exactly what you want to do, albeit in a VERY different vehicle.

PM me, (or [email protected]) and I'll find the video for you. However, if you decide you don't like the above mentioned transmission, let me know, I love them to DEATH!

Actually it is a Muncie transmission with the designation sm420. the "Muncie" transmission plant merged with the "new process" transmission plant that dodge owned forming a joint venture between dodge and gm. The new line of transmissions they built are called the "NEW Venture Transmissions". The NV4500 has some of it's pedigree from the early design of the sm420 and sm465.

The SM 420s weren't made at the Muncie plant, nor were they made at Saginaw. Those plants produced mainly 3 speeds (car and truck) and passenger car 4 speeds. The SM 420 and 465 were actually made at the Toledo plant.
BTW, the "SM" designation on GM manual transmissions stands for "Syncro-Mesh", which was developed by GM in the mid-'30s.
Also, "New Venture Gear" is the GM side of New Process Gear, with the older name being the Chrysler side.
One more thing, unless you can dig up all of the components to do the 3 speed swap, I would suggest using the T-5 as well.

As I said, "IIRC, if it's a granny low, it's not a muncie, it's a saginaw. Regardless, ...."

Emphasis on the 'Regardless'. I just wanted to help. Sorry.

Hi
I just found a set of 3 photocopies for a STANDARD 3 speed, column shift There are 2 cut-a-way views and 1 exploded view of the transmission itself. No linkage or anything. I copied them from a service manuel at the Dallas Public library years ago and just found them. If you need them I will try to scan, but more than likely need to copy & mail.

Brad