If its anything like the 164, (beleive the V6 & TS boxes have the same casing) the gbox dipstick is halfway down the side of the box, on the bulkhead side.
1st thing you'll need to get at it is a 2nd joint in your arm
To access from above, you'd need to remove the inlet rubber hose & a variety of other items.
From below, it requires a little manual dexterity, but is probably easier..
Look for the gbox drain plug & follow its line up.
If you want to fill the box, use the reversing light switch hole (22mm deep socket)