So during a recent bout of repairs on my truck I had the gears/clutches in the rear diff replaced. The shop didn't say anything but I remember reading that I have to change the diff fluid and friction modifier 300 miles after the gear change.

Do I still need to do that, or should I just leave it alone?

 

Probably wouldn't hurt. Mine needs done as well, Called the dealership to get a parts list to replace bearings, seals, and clutches in limited slip, they told me I didn't need friction reducer. Wtf.

 

you should run a thick gear oil for about the first 500 miles then replace it with 75-140 i believe someone correct me if I am wrong

 

My buddy that owns a tranny/diff shop would always change our friends gears out every few weeks for drag nights and he would always put a quart of the regular Lucas Oil stabilizer in then change the fluid after a few days with regular/recommended gear oil. This was on a 73' Nova so I'm not positive if that would be ok to run in this application with the LS but I can't think of any reasons why it wouldn't be ok..... lol