Snapping wheel and axle studs

[bw32056]

G'day my names Ben, first post as I am at a loose end after 2years of trial and error with today seeing my rear wheel sail by me, luckily as I just pulled up.

History - 75 Series 1990 model with 730K on the clock, about rebuilt this cruiser but have conundrum I cannot figure out.

Broke 6 sets of axle studs in 2 years (bought it 2years ago). Tensioned nuts at 25nm, the nuts come loose every 2 days 200km, only on the drivers side. I would re-tension them but diff oil would leak out due to the gasket tearing due to losening. Take it on the sand but rarely offroad, 95% driving is my run around, only ever broke them on the road and usually at high speed, freeway etc.

I have replaced hub, bearings, even got a new drivers side axle as thought maybe slightly bent.

Finally decided to drill and tap the right rear hub out to 10mm to fit 105 series studs, also gone through 2 hubs prior.
This was 2 weeks and about 600km ago and then today my left wheel came off when 1 wheel stud snapped holes elongated on the steelies and wheel nuts ripped off.

Had 1 person say it could be a bent diff housing. Ok if it is but also $2K for a new housing, something I am hesitant to do if it isn't the issue. I do have non standard wheel/tyres on it that are heavier than usual but surely it can handle that?

Anyone ever heard this before? When buying the car it came with spare axles, now thinking it's been a long standing issue with this old girl, just lookin for answers and how to test the issue for what t is before I part with the $$ and find out it not the issue.

Hoping someone with experience has seen this. Thanks!

[32V8]

Put a set of standard wheels on it and your problem will disappear. It is critical that the hole in the wheel centre is a snug fit on the axle boss (without wheel nuts fitted). If your wheels are sloppy on the axle boss this allows excess force on your wheel studs and they will break, as yours are doing. If you are unsure of what to do, go to a reputable tyre shop and get assistance.