2008 GT 500 Need advice on rear end

I have lost fluid out of the breather at the top of the differential on two different occasions on the track. The first time Ford said it was overfilled at the factory; to correct they lowered the fluid level.

No problem on the track until I change out the ring and pinion. Differential probably got filled to the bottom of the fill hole, as noted in the Maintenance Specifications. Next trip to TMS and I came back with a pint of 75W-140 on the undercarriage and rear breaks, which cause another set of problems.

The rear axel is picking up a lot of heat for the rear end, axles, breaks and exhaust. Anyone else having this kind of a problem?