Update: When I removed the carrier to try the .015 pinion shim I noticed I had not seated the differential carrier bearings down to the carrier shoulder stops. After seating them properly I tried the .015 pinion shim and the gear pattern was way too high on the ring gear. I removed the .015 shim and replaced the .018 shim, set the backlash at .008 and the pattern was perfect. Per Patrick's 3.55 swap instructions I let the truck idle in high gear on jack stands for 15 minutes and then drove tthree 5-10 mile runs with cool downs in between. The truck drove great.
I do have a constant ATF leak between the lower transmission extension housing, seat, shims, 6 bolt collar area. I removed and checked the O-ring on the seat and it was properly seated, along with the thin paper shim on the collar. Re-torqued to specs and it still leaks. I'm probably going to remove again and apply Permatex "The Right Stuff" and reseal. I've always had a small leak in that area and noticed when I first disassembled that area it was loaded with silicone. Thanks everyone for your input and suggestions.