I think it's either the 122 or 124. I can't find any markings on it that identify the model. There is a black nut on the top right front with a screwdriver slit in it that has a dip stick attached. About half way up on the front and back toward the center there are "bungs" (like differential). I know the back and front have separate reservoirs and you remove the back bung to check the rear reservoir oil. I know the oil is supposed to be level with the back hole. It does not have a dip stick in the back. There is no sight glass on the unit. Don't see any drain plugs. It's a lot like sex, a lot of confusion and I want to make sure I'm doing it right.