Allen wrench plug to drain front diff, what size?

Greetings, anyone know what size the allen-wrench is that will drain the front diff, working on a '99 us-spec Cruiser, which has allen-wrench plugs for fill and drain, I did not expect to find those. I'm guessing 10mm, since it looked about that size. I have to go out here in a few minutes to buy a wrench for them.

Thanks,
Mark Brodis

I bought an assorted set of allen wrench style sockets. I think they were labeled as being used for brake applications. Worked for me.

I am not sure since my 99 use standard 14 mm hex plug. Most likely it would be 14 mm or 5/8"

It is a GM brake allen wrench, get a brake allen wrench set and you will be money. Which speaking of the front diff why did they use nice proper bolts for the rear and transfer and then the front has a little allen? That helped because the previous owner did not tighten that allen down to about 1000 lb/pounds.....

Well the actual size of the allen is 10mm. I went this afternoon and bought a metric allen-socket set from Home Depot, largest size in it is 10mm and that's perfect. Ofcourse this one has a bit of rust, so had to somewhat pound it in a bit. Also those plugs were TIGHT, not torque type tight, just crack it loose tight, but I had to use my 18" breaker bar to crack them loose.

I didn't have a gearlube pump to fill it up again, used a hose into the hole in the diff, then up to the engine compartment, into a larger hose (snug fit so no leaking), then onto a funnel, worked perfect, actually way easier and better than even having a pump. Gearlube actually looked pretty worn, which I was surprised, vehicle has 46K miles on it, a fair amount of surface rust underneath also, I think I'll touchup some spots with some paint tomorrow to keep it from rusting more.

I was sposeto do new front rotors, pads, etc, all that shebang, however, awesome UPS screwed the shipment and it'll be delivered tomorrow, when I leave (only here for the weekend to do this work)...argh!!!

-Mark Brodis

Cruiser4UGA said:

It is a GM brake allen wrench, get a brake allen wrench set and you will be money. Which speaking of the front diff why did they use nice proper bolts for the rear and transfer and then the front has a little allen? That helped because the previous owner did not tighten that allen down to about 1000 lb/pounds.....

Click to expand...

Actually, both my rear diff, and transfer case had allen's. When I bought a new rear diff plug from Toyota, it was a regular hex. Go figure.