I've got a '55 GMC shortbox stepside raparound back window that was converted to a 4 wheel drive before my dad bought it ten years ago. He wouldn't let me touch it until he gave it to me this past winter so as soon as I get some money (yea right) I'm going to finish it. I'm not even sure what it is sitting on but I'm guessing it is a 73-87 SB frame. I don't know if it would help since you are doing a LB conversion but I could take a look at it and post some pics if you want to see anything in particular. Let me know if I can help.