I have a 1991 F150 4x4. 5.0. 5 speed manual, lifted with 38.5" super Swampers, d-44 scissors up front and 8.8 on rear. has 4.56 gear front and back with detroit lockers. Well, the locker in the back broke after I discovered a loud pop in the rear . Did not stress it. I have given this truck to my son and he is fixing it. Yesterday, I bought 2 8.8 rear ends from a guy for 100.00 total and my son went & picked them up.

He and his friend pulled out the broken locker form our truck, and then he pulled the non locker component from one of the other stock rear ends. They went to install the replacement when they discovered that because of the 4.56 ring gear, the non locker will not fit, as a pin they say gets in the way. Only a locker will go in. My son does not want to fork out 500.00 or so because he says that it will only break again since this will be his driver around town for a while and lockers don't do well on pavement. I thought there were lockers that were auto and did not lock on pavement and sharp turns, but only engaged when needed. Please offer any advice for my situation. I know going to a 9", d-60 or 70 is the right thing to do and is what will eventually happen, but for now, he wants to get it going.

This truck is not a rock crawler or heavy duty mudder.

 

Ur right beefing up the axles would be smart. What you are thinking of is a limited slip and today they come stock on a lot of new trucks, lockers only engage when you want them to (Detroit, ARB or Eaton to name a few), spools are what your son is thinking of. Spools are used on rock crawlers and mudders, they totally lock the axle, 24/7/365. Sick truck btw.

 

You will need a notched cross pin to fit the 4.56 gears on the replacement 8.8. The stock pin, as you have noticed, does not fit. If you google any differential 4.56 gear for the 8.8 there will be a note in the description stating this fact. Here is an example. http://www.ringpinion.com/ProductDet...px?ProdID=1945



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