How hot does the diff typically get? I just installed 4.56's and a Valuetrac and after the first 30 minute break in drive, the diff cover was pretty darn hot. I could only keep my hand on it for 1-2 seconds. The diff housing itself was hot but I could keep my hand on it without burning. I put in 2.5 quarts of oil, which was up to the bottom of the fill hole.

 

It will be warmer as the gears are breaking in. Should cool down after you put some miles on it.

 

X2 ^^^

My 14 bolt was hot as hell after the break-in drive.