???????---the rings holding the large TABs are welded to the axle tubes--not part of the trailing arms. The $520 price would seem to indicate a road service job. If you're thinking of swapping the rear your original has to come out anyway--why not drag it to the (any) welder and have it done at Goatman's suggested price of $20--or something close. Without having checked my collection of owner's manuals I do believe the gear ratios would be different between the '78 and the '83. -- Dave