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-   -   Swapping a Muncie SM465 to a TH-350 on a FS Chevy Truck (

TL-Iguana 08-22-2004 12:43 AM

Swapping a Muncie SM465 to a TH-350 on a FS Chevy Truck
I wrote this post to try and help the people out there with a 73-87 Full size Chevy pickup, that are looking to swap the Muncie SM465 with a TH-350 Transmission. I have seen many posts on different boards out there with people looking to see if this is possible, yet with no replies. Well it is, I have done it. I just hope by posting here that it will be of use as this is the largest, most informative site on the net!

I did this swap on my 78 Chev 3/4 ton, with all the parts from my 73 1/2 ton. I basically took out my muncie SM465 (granny low 4 speed manual) and replaced it with a TH-350 auto. This was done in my home garage, with no special tools. Just a lot of grunting, and brute strength to lift that puppy up there! This is for the most part what you need to complete the swap. From a donor truck, or your local wrecker, grab the steering colum with the shift arm, (unless you use a floor shifter), the transmission cooler lines and transmission cooler, or a radiator with it built in, the flywheel that came off of the truck with the auto, the torque convertor and the bolts that held it to the flywheel. If its a Muncie 4spd w/ granny low, the cross member on your truck is like a big "U". This will line up with the holes on the auto TH-350, but you will find that the vacum modulator will hit, so if you dont want to notch out the original x-member, replace it with the "straight" one out of any 73 to 87 truck with an auto tranny. When you take out the old manual and clutch assembly, you will be removing the neutral safety switch at the back of the pedal as well. Make sure when you have the new tranny and steering colum in, that you re-hook up the neutral safety switch wires to the new colum. If you dont do this, it won't start. If you bypass this, it may start while in gear, and this would not be ideal. The linkage that goes from the steering colum in the engine compartment, to the tranny itself, and the kickdown cable that goes towards the carb are also required. It wouldnt hurt to get the speedo cable as well, as you may find the orignal too short. You will more than likely need the driveshaft from the donor truck as well, just the front section can be changed, but you may need to get a different sized U-joint. My 3/4 ton had larger U-joints than my half ton donor. This was swapped with the use of an adapter U-Joint. And last but not least, A LOT of time and PATIENCE.

I Hope this helps you all out, and I hope I didnt miss anything critical! If I have missed anything please post after me, as there is a lack of information on this subject. I have done my best to provide correct information, but such a swap should really be done by a professional, or at least with the guidance of someone that is mechanically inclined. I really hope this helps you all out, as I myself spent 3 months trying to find information that was non existant on the net. This swap can be done on a 4x4 as well, and more information can be found here,

If you have any more ?s post a reply, and Ill try to keep my eyes open on this!


stu 08-22-2004 05:54 AM

A bit extra.
If you are having problems with the cooler lines.

I use 5/16 steel brake lines with the steel coil around the exterior.
They can be bent, twisted, cranked on and not kink.
Plus the steel coil protects them from abrassion.
They come in various lengths. A 4 foot section will do one line.
But then in Canada it wouldn't be a 4 foot section eh.
It would be in millipedes.

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