What I know is that the rear end assembly is basically a Ford product. I've got over 29K miles on my trike and I need specific details on the rear end, specifically how to change the gear oil. There's no drain plug on mine so that means I probably have to pull the 8-bolt differential cover to drain it. However, I have not been able to locate a fill hole for the oil. There is what appears to be a vent port just to the right of the differential case with a hose attached to it. Is this the fill hole? Also, what is the proper amount of gear oil to use? The documentation is pretty specific about having to change the gear oil but it doesn't give directions on how to do it. The closest dealer is a 220 mile round trip and there's an issue with the auxiliary gas tank that's mounted right behind the differential case. It has to be pulled to get the differential case cover off. A little help please.