SBU front diff fill plug inaccessible

So I ran into an issue while trying to change the oil in the front differential.

Notice that the check/fill plug is right where the pan hard rod goes across. I could not fit a socket Allen in there at all.

I tried jacking up the driver side of the truck hoping it would move that bar out of the way – fail.

I also tried undoing the bolt for that pan hard rod – It is extremely tight and I would have taken it off if I had to but I don’t feel that taking that bar off every time I want to check the diff fluid level is really a practical way to go. Especially if it is always as tight as it is now. It is really hard to get leverage down there to break it free.

The diff in the manual is totally different and would solve this problem. Turns out that these are the heavier duty two-piece axles – mine are three-piece.

While there are special European wrenches specifically designed for differential drain plugs which solve this problem, having a special tool just for that one bolt seems a bit silly to me.

My solution:

I ordered a 14mm Allen wrench for about $14. I had to cut 5/16” off of the short end for it to fit. Worked perfectly after that. So, I guess I do have a special tool now but it was relatively inexpensive and it can still be used as an Allen for any other situation.

Other options:

One could order a new plug and weld a normal nut onto it. I would assume this would work – maybe some day.

One could order the special wrench. The space between pan hard and plug when tightened is 35mm.

I did try jacking up the chassis:

This is Allen placement before lifting:

And after lifting:

So, it actually made it worse. I also tried lifting the axle on the right side but that had no effect at all.

Conclusion:

I still think chopping down an Allen wrench is the cheapest ($14) way to go. It also doesn’t require any extra work like lifting. And, the wrench is still usable for everything else after modification. You could use it for both diffs and the main transmission.