I think the bellhousing search is a little wider than '63+. The bellhousing from a '55 to '68 V-8 powered truck will work.

I'll also add that you will either want the bellhousing crossmember from a '54 or '55 1st pickup or you will need to make adapters to mount the bellhousing on your existing bellhousing.

1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble...