Ive used JB Weld and had good results.

If it is a crack, you can grind out some of the material clean it properly and use this product. Devcon. look it up industrial aluminum epoxy,repaired Honda transmissions with it and cars still running. bit expensive at $80.00 for the tub and hardener.

Minsuki.

Without taking it all apart you'll never know if it is indeed a crack - it may not be.

Back in my yoof when I was young and peniless, I Araldited (our generic term for epoxy) a remote gear linkage back onto the diff housing where it had been cracked off.  Worked a treat.

Remembering that last year while working on a friend's car with a cracked diff housing, we dug out the crack on both sides and liberally filled it with epoxy.  13 months on and it's still oil tight and working fine.

It may well be saveable without running he risk of weld distortion.

I agree with Kelley ! I have seen some pretty nasty looking castings which appear to be cracks but upon further investigation , turn out to be casting flaws or flash. I have also run into this at work on Cummins Diesel engines. I would clean thoroughly with some brake clean or similar and if you have a magnifying glass . I use the 'mag light ' app on my IPhone if that IS a crack you will definetly see oil leaking . Good luck .....

Mousy

There is a chance that it's not a crack. Aluminum castings sometimes have marks on them similar to this from the casting process. I would either sand or lightly grind the surface of the crack to see if it is really a crack. Even running a file over the surface would give you more information. I would expect to see oil seeping out of a crack that long. At a minimum clean and observe the area for oil seepage.

Kelley

Usual cause of this crack is someone has broken a diff pin, it has come part way out and walloped the casing.
Also check the back of the gearbox's centre web when pulled apart, as that can get hit too.

The alloy TIG welds pretty well if you can't find another diff housing.

I think I would want to find why it cracked first? MMmm welding oil bathed Alloy my Fav. job.............................

Steve, you are more familiar with gearbox housings than I will ever be.  Could that housing be HeliArced or would that make it distort too much to fit properly again?

It does not look good. I have had so many bad rod change cases lately I may have a spare diff. cover. It may not be a perfect fit but we have been swapping diff. covers around for years. Contact info in profile. Steve (CTR)

I took the subframe off the body and I started cleaning it.  I think I found the source of the oil leak.  Here I thought it was the lack of cup washers on the tappet covers... ha.  If you can't tell, this is the housing between the drive shafts.  From my research, it looks like I'm going to need a new transmission.  Someone please tell me otherwise.  I just can't afford that right now.  Is it possible to get it welded?  It looks like it's aluminum.

Jamie