[Peanutbutter]

as near as I can tell right now both my C 80 and the GMC B have identical front axles. Both are 7.20 ratio and I'm in need of a ring and pinion for the C 80, mine has some bad spots on the pinion. The napco front axle gear uses a GM corp rear diff carrier, still trying to identify which one. They made a 11,000 15,000 and 17,000 lb diff, the tooth count is 5 and 36. The only thing I can tell you is the ring gear is 12 1/4 inchs in dia. and I'm fairly sure its the 15,000 lb carrier. there might also be a 13,500 lb carrier out there, another problem is the rear diffs used fine spline axles and the napco fronts used 10 spline so the side gears have to be changed.