what is the rear end under a stock 61 GMC half ton 2 WD called? it is a 6 bolt with the removeable third member and I think they were the same from mid 50's through 62. I'd like to price a replacement ring and pinion for it but not sure where the lowest prices are or what to enter to search them. I'm kinda thinking I'd like to get 3.38 or less ratio. my old 305 sure don't need to be spinning the 4.11 on the road.I'm kinda partial to the old granny gear 4 speed and they are pretty much bullet proof. I'd rather step up the rear end and keep the rest as is.