Anyone know where I can find ring and pinions for my truck. I am at an actual mounted/loaded tire height of about 32.2" with 3.73 gears on an 48RE and it's spinning 1600 at 60 mph in OD and 1900 at 70 MPH which is too low to pull heavy and in 3rd gear the RPMs are too high for me to want to run that consistently.

I was thinking of 4.56 so that I can really use all 4 gears.

"Usable" RPMs and speeds...

For a 4.56 in OD:
55mph = 1800 rpm
60 mph = 2000 rpm
70 mph = 2300 rpm

and in 3rd:
45 mph = 2100 rpm

 

Have you looked in Jegs or Summit? If not, maybe a call to AAM themselves and ask who one of their wholesalers is.

If push comes to shove, I bet you could find someone to trade diffs: 3.73's for 4.10's; trucks side by side. Bet it would be lots cheaper to do it that way too.