If you mean the tensioner pulley, they are the same in how they work but they look different. My original '85 flew apart on me..the bearing busted and the pulley flew out from under the car and shot out like a rocket...lol
If your asking about fitment my I'm using my 1983 tensioner pulley on my fuel injected 88. Also the 88 tensioner fits on my 1983, they look a little different. The only real difference is the 88 has a bolt that runs through the center where you bolt it to the bracket and the 83 doesn't it just has a permanent stud that's attached to the back of the tensioner. But they fit either model, if this helps in any way.