One thing that caused me lots of aggravation was the rear pilot hole. I have an 02, bought a rebuilt 03 short block, swapped all the stuff over, motor went in nice, then the frustration of mating up the trans. After many hours fighting it thinking I must have alignment slight off, I measured the torque converter snout and the crank recess. The crank recess was much smaller on the 03 then the 02. The 03 actually has a spacer installed to make the hole smaller. It was a bear to get out of the crank, but once I did, ****** went in nice. If you are using a different year engine, check it all before installing and finding out something doesn't mate up. I was pretty fortunate with everything else during the swap though.