I have a 2003 Extended cab XLT Sport with 3.55 limited slip gears. I am wanting to put a alum or chrome rear end cover on it, so I guess I need to know what rear it is. Are these like a 8.8 or ? Also, when I change it out, I assume from other threads that I will need full syn 75-140 fluid plus I will need to get some friction modifier as well, right? Looks like 3 quarts give or take? Thanks!

 

You didn't mention what engine you have. If you have a V6 or a 4.6 V8, you have the 8.8" rear. If you have a 5.4 you have a 9.75" rear. If you don't know what engine you have, look at the axle. If the pumpkin is round, its a 8.8" If its sort of oval and has 12 bolts on the cover, its the 9.75" If you need picts I can find some and send, but the difference is really clear. Hope this helps you.

 

The friction modifier is for the limited slip version.

 

Most auto parts stores will have rear end lube available with the friction modifier already in it. Look for the bottle that says "specifically designed for limited slip". Buy that stuff and you don't have to mess with guessing how much modifier to add.

 

Thanks guys...must be the 9.75 rear as its got the 5.4l engine. I forgot that piece of vital info in the orig post! Thanks!