12-Bolt Advice Needed

My bracket race car is a 71 Monte Carlo 408 BBC with T-400 & 12-Bolt Rear. Eaton Posi unit, with Richmond 4.10 gears. Heavy Car, (3750# without driver), fairly mild combo. (12.30 @ 108, 1.71 60').
Problem: Broke a Spider Gear (pinion Gear) last season, which trashed pretty much all internal differential parts. Replaced posi with identical unit, which was in very good condition. New R&P gears, bearings, etc.
10 races later, (72 passes), I was pulling routine maintenance, and Cross-shaft in Posi unit is severely galled, as are the spiders that ride on it. Had been using synthetic 75W90 oil for years, when I repaired it last year, Richmond suggested petroleum-based 85W140 instead. The cross-pin is very poorly lubricated, but this is incredible how bad it got chewed up, and how quickly! Okay, 3 questions:
1. What caused this rapid failure? Cross-shaft was "Yukon" brand - could be Chinese sh!t metal?? Or weak clutches in posi, causing single-spin?
2. I cannot get the cross-pin out, I beat on it for almost 2 hours, and it is halfway out of the housing. So I cannot remove the axles, or the carrier. Do I need a cutting torch to get this shaft out? Or?? Anyone had similar experience?
3. Pretty-much decided to go to a spool. I have some GM axles with C-Clip Eliminators on them. But no installation instructions. I am told I have to cut the ends off my axle-tubes? Anyone done this before, or have some instructions on what I need to do to use these? Looks like the bearing retainers are split in 2 halves, do I sandwich the backing-plate flange between the 2 bearing blocks?
Thanks in advance for your help.
-Jim.

It sounds like the pin has worn a lip on it that is catching.
Can you turn the pin at all.
Turning it should free it up to get it out.
Good luck.
Ken