Up for sale is a Yukon brand 3.73 ring and pinion plus master install kit. I bought this setup about a year ago and it hasn't left my living room since. It has never been installed and its till in the shipping box. The gears are for a GM 12 bolt rear end found in the mid 70s up to the end of the 80s with 6 lug axles. I bought the gears for my 1981 suburban to change from 3.08, but after looking at the work involved i decided to just change the whole axle. I payed well over 500.00 for these from Randy's Ring and Pinion. I would like to see them leave my living room for 250.00. Again, never used, still in the Styrofoam.