Being the amatuer I am I forgot to remove one bolt from the tranny housing and to make a long story short I cracked the housing around where the engine pin goes into the tranny. Its a TH-350 so I think its cast and not aluminum like the powerglide (I think). Can this be repaired with a weld or am I gonna have to get a new tranny. I am removing the 327 for a 350 HO crate engine.

Yes It can be welded but I would suggest you borrow a bare block to bolt it to while it's being welded. Aluminum can do weird things while it's being heated, especially near the alignment dowels. We repair cracked aluminum cases all the time this way and don't have problems.
Jim

Thanks for the reply Jim. It is aluminum then. Didnt know that. I will try to get someone to weld it for me, but I am not sure if I know someone that is experienced with welding aluminum.

It is CAST... ALUMINUM ! Follow Jim's advice.