Friggin pinion nut not breaking loose....

This would make this easier. You have a photo of one you’ve done?
No pic's
I have done several
Looking from the rear of the car
- Slightly right of center mark and drill a hole for a 1/4 NPT flush plug
- Tap the hole and clean up any metal chips
- Apply some pipe dope to the plug and install
Job over it's about as simple as it gets and it saves a big mess when you want to change out the grease.