Yes, pinned on brake side and lock collars on the other. If you run APC hubs on the right, put the axle sleeve on and no collars are needed on bearing or hub!
You want to pin the axle on the side the brake is on. The newest PRC axles are drilled on both ends to accommodate the RR brake on the Triton and Triton Jr.
Seat size? Driver size also can change it a little. We typically mount them 8 1/2 from the axle to the top of the seat and about 4 1/2 of inside edge of inner engine rail. If running a Med or Large 2.0 go 1/4"-1/2 higher.
Did the RF Spacer get taken out from first scale to second?
During your practice season did the LF hit any disc blades?
When on the scales lift the rear end and spin axle 180. Those Hoosiers can be very out of round.