1995 Rear End Swap
 

I have a 95 f150 4x4 with a bad rear end and I just found out that it has 3:31 gears...I have looked all over and I'm only finding rear ends with gears that are 3:55 would it make a difference if I put the 3:55 gears on my existing transmission??

Then you couldn't use 4x4 because front and rear diff's have to be a match.

Quick answer: Yes you can swap the rear end.

However as raisin pointed out, your 4x4 will be affected. To use your 4x4, you would have to swap the gears in the front to 3.56:1 to complement the 3.55:1 in the rear. Otherwise, when your four wheel drive is engaged, the front wheels will be attempting to rotate faster than the rear wheels. Big issue on any dry ground.