There is a 4:10 third member on Ebay right now from a 67 - 72 Chevy 3/4 ton - # 7900609800 (sorry dont know how to link). There is only 1 day left so hurry. I was going to consider this swap for my 48 - 3/4, but I dont want to pay the shipping on something this heavy. Not even sure that this is the right one. Good luck anyway.
Ralph
