1K9
No'mo Rocket 4 me
Rick the problem is not usually taking the bolt out it is when you tighten it, the torque setting is extremlylow(cannot remember what) and trust me you have to use a torque wrench.
No reason to change the final drive oil frequently no reason at all in fact 10000 miles is about right.
First time I changed it, looked like it was the factory oil. Checked 5000 later, looked black so I changed it. The rear tire is about to need a change and the splines need to be checked for lube so it's a good time to check it.
Drain plug 15 Nm. Fill plug 60 Nm. Nn not lbs.
Bevel box bolts sit cross tighten to 20 Nm and re-torque to 64 Nm.