I don't have a wobbler (maybe I should get one) but I do have a universal extension, unfortunately it adds too much length. I'll give the box wrench to the allen another try, using a second box wrench to the open end, or a cheater pipe to gain leverage.
I'm also wondering (now that it is morning and I have a clearer head

), could the fact that I have the car "floating" change the relationship of the diff to the leveling valve/lever/etc? What I mean is the car is on stands and the rear suspension is at full extension. Would having the weight of the car on the suspension (on the ground) allow more room to access the fill plug? If so, I may just wait until she's off the stands.
__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.