I've twisted off three stock A body 8 3/4 axles drag racing, all of them twisted off at the end of the splines closes to the wheels
On your deal you could use some wheel bearing or thick chassis grease on the splines and then reinstall the axle to see how far the splines are engaging into the posi unit or spool
All the stock Mopar axles have rolled splines on them, not machined like some of the better after market Hi Po axles
A friend of mine twisted the end off of one of Mark Williams 30 spline 8 3/4 axles, it had been in a stick shift 340 Demon for a lot of runs, he had removed it and saw the left axle splines where twisted about 1 1/2 spline from original
I told him to swap the axles form side to side It broke off 3 to 5 runs later in his E/SA automatic Demon, that axle shatter on that end between the splines and the other axle end, it did not twist off
I thought all Mark Williams race axles had a life time warrenty so I told him to call them, he did and they said it was 10 yrs at that time, not lifetime any more
They also told him to NEVER reverse or swap the axles from side to side after one run
He bought a cheaper set, maybe Mosers or Currys, and never broke another one
On your deal I wouldn't worry very much about it unless your going to race it a lot at the track with good slicks and lots of traction