Over the time I've owned my car I've always aimed to replace bushes with something stuffer when it came time to replace. Just recently I replaced the gearbox mount with a solid filled version of my own brewing and it has perhaps done more damage than good. Firstly it raised the 60A up more into the tunnel, which is what I was aiming for but now that I have finally blown a diff ( and perhaps the replacement) is it possible that the increased angle of the box has angled the diff so under high load corners the pinion bearing runs dry, or by that same thinking is it possible that my gearbox output bearing is being run dry? The rear isn't lowered essentially.

Its not great running solid gbox mounts. Ange kept blowing gear bixes from similar pinion angle issues and solid mounts.
All sorted now

what if I pull the rear suspension down\up? those after market mounts are weak as piss and nissan ones look solid as

actually my car used to run a combo of solid engine mounts and rubber gearbox mount. it was the incorrect uni
joint phasing that was the cause of the broken gearboxs. im now running solid engine and gearbox mounts and its all good
because the driveline angles are correct. so solid mounts are not to blame, although i dont see a need to ever run them in
a road going car.

lifting the gearbox higher will change your driveline angles slightly and most likely cause premature wear of your
uni joints and maybe some driveline vibrations, but i wouldnt expect your diff to fail instantly because of this.

if i were you id be going back to a factory rubber gearbox mount which will transfer less vibrations through the car
and most importantly return the driveline back to its correct position. it may even make your suspected broken diff symptoms go away

Here's the longer version of events, make up your own opinions as to what is to blame.

The old diff:
- back lash galore
- leaking

When I installed the stiffened mount it raised up the end of the box about an inch or so, that mount surprised me with how saggy it was straight out of the packet. First drive and only noticed the lightest whining ect. Along comes the weekend and a come & try day at the local track and I enter it. Two corners in and I remember how crap the rear end of this car is, it's lifting the inside wheel like a dweeb. Two laps in on a sweeper and I hear the worst noise I could possibly imagine in 3\4, there was a harsh scratching and a massive grinding whine. The scratching was some bolts scratching the tail shaft, cut excess off the bolts and running another tail shaft thought I suspect it is probably fine. The Sunny shaft in it is sitting 1\2 way on the yoke, and doesn't have an oil splash hat, the box does have the big version on its output seal.

I managed to drive it home (albeit slowly) and put it up on the stands to investigate. I 4th gear the rear end was quite visibly twisting with any application of torque. I can't actually get the gearbox drain plug off to inspect the oil for shavings (I swear they used a whole bottle of loctite or something!!, I've tried a blowtorch to try and break the bond). The diff oil did have shavings, and quite a lot of metal dust to boot. So given those circumstances I pull out the diff, clean out the shavings and throw in a slightly less crap center.

Upon inspecting the original center I could only find signs of harsh wear on the crown and pinion, the bearings (couldn't see the pinion bearing) appeared fine.

Anyway come this morning and a long sweeper corner brings back the harsh whine in 3rd\4th, I have driven it far more sedately since.

Would running a shorter shock keep those angles in check?

Ange I will try the old mount again over the weekend or perhaps but another aftermarket one and set it solid at a different level, I just can't stand how they flog out so much.