i have 2 trucks one is a 1974 3/4 ton and one is a 1986 1/2 ton the motor in the '74 is brand new but the rear end just locked up so i was wondering if the rear end from the '86 1/2 ton will fit/work under the '74?? need to know asap, and if at all possible try to email me if you know at Superdude4agze@aol.com

It should bolt up fine as far as the spring perch/mount. The problem you may have is at the universal joint. Most likely the '74 will have a 8-lug Dana 60. The 86 could have a 5 or 6 lug, 12 or 10 bolt. The quickest way to find out if the universal joints are the same is to call your local parts store, tell them you want rear u-joints for both trucks and see if he gives you the same part numbers for both. If so, then all you'll have to do is swap rearends(but you'll have 5 or 6 lugs in the back, and 8 lugs up front :(). If the part numbers are different, you may be able to swap "bearing caps" on the u-joints so it'll work.