1985 Monte Carlo SS known as Barney

[Vegas69]

Forgeline told me that a wheel will flex 2-3mm under extreme load.

I'd say this is your red flag for the axle leak. You need to get those axles moving in and out less. Check the end play with a dial indicator and see what you have.

Car looks great by the way. My first car was a 1981 Monte with a 327. Totaled it....haha