i know my 8.8 is at a angle, but the fill plug is on the opposite side of the diff, near where the pinion is, but i just filled until i felt it had enough, it took over a gallon! but for the 35 and being on the other side, if you wanted to do something i would jack the right rear tire up and angle the vehicle that way then add more.
You can search the specs in google as to how much fluid it should hold from the factory
95YJ 2.5 AX5 NP231 HP30 4.88 and aussie, 8.8 4.88 mini spool, 4" RC, 1.5" Boom shackles, 1" BL, 1" rear stretch, 36 12.5 15 TSL SX's, trimmed front fenders, bedlined exterior, comp cut coming soon!
Build thread: http://www.jeepforum.com/forum/f22/b...-dirty-894483/