Pinion bearing ?

which pinion bearing??
I had a new gearset and bearings, so the rear bearing (the one by the head) got pressed on, after i found proper pinion depth ( i bought an extra one and machined it out to have a snug but slip fit so i could disassemble and reassemble easily until I got the right pinion depth. the new bearings are so close in tolerances that when you put the actual press-fit bearing on, it will still have the same depth.
the front bearing (small one) is also a pretty tight fit, so I used the old front bearing to get a close shim pack (solid spacer) and then used the yoke and nut to get the new bearing on. the shim pack wasn't right with the new bearing, so I had to press the pinion back out to adjust the shim thickness. since I got a preliminary thickness with the old bearing, and added .003 to it for the first new bearing fit, I only had to press it out and back on once, so I could add another .001 to get the preload right

HOWEVER....a lot of people just use the crush sleeve so they don't have to worry about solid spacer shims....

(i did this with a 489 center section)