Many options, used mustang II, subframe, S-10 may work but be sure to get the extended cab frame and you'll have to cut out a portion of the frame to get the right wheelbase. regular cab will be too short. If you go subframe try the G-body GM's 77-87 I believe, Monte carlo, cutlass, etc. The wheel across on those is 58 inches, mustang II is 56 inches, your chevy is probably closer to 60 inches.