66 gmc c10 transmission swap to sm465

[danieljpeter]

Hey all,

I'm not too happy with the transmission that came in my 66 GMC. It was the factory 3 speed, I think an sm-318. It was 3 on the three, and someone converted it to a floor shifter. The shifting action isn't really great, kind of sloppy and inconsistent. Plus the shifter is all the way over to the left of the tunnel and my leg hits it pretty hard. In addition, I have some clutch chattering. I also could use a lower first gear. So I decided to pull the tranny and do the clutch and reinstall a different tranny.

The SM465 is a great truck tranny. Really plentiful, cheap, and durable. It is also top-loading so the shifter will be in the middle of the tunnel away from my leg. So I picked one up and I'm having it rebuilt so I can be confident it is good before I go through all the work to install it.

The truck has a good running 327 in it. It has the bell housing with the motor mounts attached and a crossmemeber right underneath. There is no crossmemeber attached to the back of the trans.

Here's what I think I will have to do for the swap:

Pull tranny, bellhousing, bellhousing cross member, clutch assembly, flywheel.

Resurface / replace flywheel, rear main seal. If flywheel is not 168 tooth, replace with 168 tooth version.

Install mechanical actuated aluminum bellhousing that will fit small block chevy and the SM465. The bellhousing I have won't work with the sm465.

Modify transmission tunnel sheetmetal to fit around the larger transmission. I can cut my tunnel along the stamped lines in the floor and get a replacement screw in tunnel from a junkyard, or just cut and weld the one I have.

Install transmission to bellhousing.

Make crossemember that mounts to rear of transmission using a new stock mount.

Probably have custom driveline made. I have a 1 piece driveline now, but I'm assuming the length will be wrong or the ujoints won't match.

Hopefully the mechanical clutch linkage will hook right up.

Hopefully my current starter will work. I may have to get a mini starter or some other replacement.

Please correct my understanding of this process if you see anything wrong. I haven't done this particular swap before, and would love to hear from someone who has.


Thanks!

Dan