Anyone know a shop in So Calif that could do this to a 75 GMC 1/2 ton?

 

Alot of those trucks from 1975-1979 were factory full time 4WD, which is basically AWD. You just need a Full time NP203 transfer case, and solid front hubs. The 203 Tcases are a dime a dozen, and should be really cheep. I know a shop up in Visalia Ca, that can hook you up. They specialise in 4x4's, and have a large supply of parts for 4WD trucks. If you are interested I will give you there #.