Joe The -R is suspicious to me... Ford uses a R to indicate their locker in the 8.8.
I would spin one wheel and count the revs of the driveshaft to find out for sure.
Look inside the drivers door post for the axel code. If it is in there post it here and I will tell you what was shipped in that thing.
The codes are availabel all over the net.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist