Few questions (rockwell T-221 swap and tranny)

[FUNMUDDER]

Hello,
First of all, I'd like to know what my 68 GMC has for a transmission. It has numbers on the top cover but they don't say the make of the tranny, just GM numbers. Reverse is next to 4th gear, if that helps.
Second, I am thinking of a transfer case swap. I read in a previous Rockwell t-case thread that a Sm465 with a Rockwell tagging along is the same length as a 465 with an NP205. But another thread that I started said I had to move the t-case crossmember back and re-do the driveshafts.
So heres my other Q: if I could get a complete parts-truck with a NP 205, could I bolt the t-case and driveshafts right in, move the crossmember back, and be all set? Are the trannys the same? Thank you for responces.