I appear to have a leak in my diff from a couple of holes that appear to be factory plugged in the cast housing. Has anyone one else had this problem? Does anyone know if they are suppossed to be welded from factory or do they have some type of sealant in them? Some original photos have not been recovered yet.

They are holes left over from casting the differential housing. They shouldn't leak. You may have developed cracks there. You can weld it yourself if you're handy, or just get another diff.

i had the same problem, have you just recently changed the diff oil? havent used a gasket? i changed my diff oil n tried to be a cheap **** and just use silicone and it started leakin in the same spot end up being leaking from the gasket up the top ha... ---------- Post added 14-08-11 at 19:34 ---------- http://www.calaisturbo.com.au/showthread.php?t=210038 check that out

It's probably been leaking for a while. I haven't removed the rear cover at all and the car hasn't been driven for ages. I recently gave the diff a degrease and its quite clearly leaking in the area of those holes. I do plan to have the diff rebuilt or replaced at some stage in the next year but for now I just want to get it passed a roadworthy so I can drive it. I could always just give it another degrease before its inspected as the leak appears fairly slow.

You have probably cracked the plug welds, I had the same problem till i finally got some traction. Then this happened 403rwhp, R33 5 speed, 3.9 diff, 235 ET streets, 11.52 @ 124mph This was the first housing i ****ed. Since then i had another with fully welded tubes that i have cracked the plug welds AGAIN, cracked the tube welds & twsted the diff mounts (LJ ones of course). Going for No3 now! Fully welded tubes (slightly different than before) & heavier mounts from McDonald Bros racing. Some original photos have not been recovered yet.

Haha, I was hoping to see that photo again.

Man that one failed badly! So I've got myself another diff and its 28 spline LSD which is a bonus. It came with some aftermarket upper arms. Has anyone seen these before and know who makes them? I'm guessing the bushes are nolethane? Some original photos have not been recovered yet.

They're Nolathane arms too. They do them as a kit. Check their catalogue if you like (available on their website). Boxed arms arm a little bit stronger than the factory ones, which helps to prevent them bending when you get good traction on a hard launch. You can also get adjustable upper arms to adjust pinion angle.

So I've pulled the brakes off the diff and am getting it ready to put in. Just looking through the Gregory's manual and I see a note that says you should not rotate the diff gears with only one axle installed as misalignment of the cones may result. I'm sure I did rotate the axle as I undid the nuts. If the axles slide back in is everything ok. If they don't I'm guessing some deeper work will be required? All good, the axles slide back in and it all still works!