The Much talked about " GM 14 Bolt " rear axle is form 3/4 to 1 ton GMC/Chevy trucks built from 1973-88. The axle in my L60 is the Optional Chevrolet 2-speed 15,000 lbs axle. I have a GM 14 Bolt I plan on installing in my 1965 GMC 1 ton & upgrading to disk brakes.