ECJ5 transmission and transfercase fluid check

hey i was reading somewhere that the transmission and the transfercase share the same gear oil:?

in that case, do i just fill up the transfercase untill it ozes out? i cannot find a fill or a drain plug on the transmission:?

is there a "badge" or tag located on eather the trans housing, and the transfercase to find out what model they really are?

what kind of gear oil do yall use? is royal purple 80-90wt to slick??

thanks josh

 

There's a pipe plug on the driver's side of the T90, mine is a square head.
There should be casting numbers on the same side just below the tower.

 

From the factory, there is (was) a metal tag on both the transmission and transfer care that carries the transmission type, the Jeep P/N and a Borg-Warner/Dana number. If it wasn't lost or removed (common), the transmission tag will be under one of the top cover bolts. Not sure about the location on the Dana 18.

All the 3-speed transmissions except for the T-150 will transfer gear oil betwen the transfer case and the transmission throught the bearing. This doesn't happen very quickly, but within a few days or several miles they will seek the same level. To fill, you take the fill plug out and fill till oil's level with the plug opening. Fill both.

I'd expect any quality 90wt gear oil will do. If it were mine, I'd drain and refill with all the same type of oil. Synthetic or not, up to you, but most Jeep transfer cases leak... you may not want to feed it's habit if your gear oil is too expensive.