You can upgrade any 63 to ?? with a front cross member from a 71 to 86. I think 71 was the first year for disc. Say you had a 64, find disc brake truck pull the front cross member, rebuild it and bolt under your 64. There may a couple bolt holes that have to drilled or elongated. It's pretty much that easy, so I've read. I have a 71 3/4 ton project rebuild for my 63.

Larry

I don't own a vehicle that isn't old enough to drink.