Ive got an 89 F150 with the 8.8" rear end. Its got the factory locker and im not sure what sort of gear oil I should use (Im pretty sure theres a special type). I also dont if it is a locker or a limited slip, because I dont know the difference between them. So basicaly Im wondering what a locker and a limited slip diff is, which one I have, and what oil I should use. Any help is great.

 

Look on door jamb tag under axle if it has a letter in the code it is traction lock which has a cluth assy to control slippage between the rear wheels. I believe a locker is both rear wheels turn togetherall the time mechanically locked.
88 book says to use ford part E0AZ19580A hypoid gear lube in both std and tractionlock but the traction lock gets 4 oz of friction modifier ESTM2C118A spec ford part C8AZ19B546 for a complete refill

 

Well thank you kindly.