Best bang for you buck would be a T-5 stick shift vs the automatic as the 216 to 350 adaptor is really pricy, not to mention the need for extra power. There are lots rear ends that would work nicely under your 53.

Your major motor mounts with the truck are attached to the bellhousing so you do not want to toss that piece for any automatic. Keep it simple!

Last edited by JiMerit; 09/17/2009 3:25 PM.

It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed