i am looking for a new exhaust for my truck. i have been looking at a flowmaster exhaust, but it only fits on an 87. is there any way i could get it to fit? on my 86?

 

I had a Flowmaster with dual pipes out installed on my '86. They had no trouble at all not even with adding the 2nd pipe. It was all custom work done at a muffler shop.
There was significant changes to the F150 in '87 so most makers of aftermarket stuff cater to '87+. If you are looking at bolt on stuff then it is much harder to find aftermarket items unless they happen to fit both old and new.

Kevin