I'm trying to mount a sm465 10 spline to a Gmc 302.
I have a bellhouseing and flywheel that is off of a 1956 Gmc 270. I know that I have to get the retainer hole inlarged for it to work. The problem I see is the 270 housing is deeper buy about 1/2" compared to the one that was on the sm465. Will the input shaft on the trans be to short? Or is there a way to make work?

Thanks for the advice,W

I am not sure what a sm465 is but here is my 2 cents worth. I have a 40 Chevy with a 302 and used a mid 50s Chevy truck bell housing along with the truck cross member and rear motor mounts. I have used both a 4 speed Saganaw and a T5 on the Chevy truck bell housing and both their shaft lengths fit right into the pilot bearing just fine. I don't know if you can easily switch to a Chevy truck bell housing on your project, but it worked for me. If I remember right, the Chevy bell housing is about 1/2 inch shallower than the GMC.

I have a '55 270 that I pulled from the original pickup. I have had several transmissions in it from the old four speed in my '53 Chevy to a T5. I made an adapter for the T5. I ran a Saginaw 4 speed for years and had no problems. I don't know if there is a difference in bell housing length or not but I doubt it. The difference in length in Chevy and GMC engines was made up in the front motor mounts. Everything back to the rear axle is the same. Lots of Chevy V8s have been bolted into old GMCs. There may be different length input shafts for the SM 465 if needed.

You might look into machining an adapter to space out the pilot bearing enough to hold the transmission shaft.
Another possibility would be to stack two pilot bearings in the crankshaft.
I am assuming that the clutch splines line up okay.
Will Willis

I pulled the input bearing housing off the transmission and turned it down to fit my bellhousing when installing a GM variant of an A833 onto my 270. I have had an SM420, an SM318 and an A833/MY6 tranny on my 270 with stock GMC bellhousing and they all bolted up equally well with no adapters of any kind.

The bearing in the end of the crank on GMC motors is a ball bearing. (At least that is what the service manual shows and that is always what I have used.)