My roommate has a 98 F-150 2wd (4.2 V6) which he lifted with 35's about 7 months ago. He regeared to 4.88s about 3 months ago. A couple of days ago his rearend let go and grenaded everything inside the diff. Now for the questions...First of all, what's the stock rearend under these trucks? Secondly, what's a good rearend to swap under there if the stock one is prone to breakage? I figured a Dana 60 would handle pretty much anything you throw at it, but maybe something smaller would work too? How involved is the swap? Any answers would be greatly appreciated.

 

It probly has a 8.8 in it now,probly the esiest swap would be a 9.75 out of a 4x4 or most 5.4s had them in the back.I dont know if the drive shaft flang would be the same but for the most part it shouldnt b to bad of a swap,also some have limited slips &3.55s or 3.73s.

 

Same thing happened to my brother's chevy, he had 37's on it.
Who did the rear end work? Any possiblity is was not done right? Was there any wining or grinding or did it just let go all of a sudden?

 

If the rear end alignment was off it would do that. In other words, when you lift a truck, the transmission and rear end need to have the correct angle of the dangle between them. The u joints have to have the same amount of swivel, or one end or the other will vibrate. I've never heard of blowing a diff because of bigger tires. Not like that 4.2 was abusing it with too much power either.

 

Outlaw Customs in Grapevine, TX did the rearend work. There was a definite whining on deceleration before it just let go.

 

your pinion depth or pinion angle werent setup right.

 

I'd be going down there and tell them to fix it. Hopefully they stand behind their work........

 

One thing about the 8.8.In stock form they are weak especially if you run bigger tire's.The first thing to go is the spider gear's and once that happen's you're just going to chew up the rear end.

 

8.8's and 10 bolt can easily be blown up with 35's under the right conditions, especially if he just has the stock carrier and spider gears in there

 

sounds like a bad gear setup to me.