L18_B110 When we sold Simon this car not as pretty looking then i will add It had a BW68 120y diff I know as I fitted it. He blew that and I'm guessing he replaced it with BW68 diffs. Otherwise he would have had to change tail shafts to go with a H150 or at least the yoke at diff end.

jeez! must be down to axle tramp then...

Im running l16 and bw68 no issues but apparently I drive like a granny. Sorry for not burnouts and drifting lol like the cool kids of today

I have just replaced the centre with the same. This latest one is very noisy (could be because I didn't change the pinion?) but it seems to have a lot more lash then when I put it in. I was thinking the centre again but maybe something else there is just tired. Maybe it all just needs a pull apart and check as it sounds like the diffs aren't as weak as I thought? Or you did something sneaky to this motor andy? Haha.
I know replacing the diff with something outrageous would cure all my problems but some of us are t blessed with abundant funding - especially those of us who are married. Unfortunately now I have bigger priorities and the old flame only gets a portion of the attention it needs. Replacing with a shortened anything (that isn't bolt in) is unfortunately something I have to realise will probly never happen.
Making it good enough is what I need and it sounds like what I have 'should' be it? Will give it another once over and see what happens.
Then I just have to get those pesky new rust spots and awesome dents (thankyou morons) and then it's going to be a mother full respray...oh time where art thou?...

On the note of the tails shaft Andy was it ever properly balanced? I have a theory that this is what is destroying the centres. Cos it certainly feels very vibrative the faster you go - possible that it could be accentuating any small problems?

The BW68 doesn't have a "center" to replace. The gear carrier is built into the axle housing.

Huh? What do you mean by that? I have been sliding the axles out and replacing the guts? It's my understanding that anything that is in the middle there is the centre? You teal long me the axles should be joined or something???

Most Datsun diffs have a removable center, when you replace it, then everthing that goes bad is replaced (except the axles).

For the BW68 when the gear carrier gets tweaked, if you replace the CW&P (R&P) then it will probably just go bad again, because the carrier is tweaked.

Crownwheel and pinion need to be treated as a matched set. You can't swap one without the other.

The centre is also shimmed into the housing - if you used the whole centre from another diff it won't be setup correctly for that housing. There will be slight differences in each centre and each housing.

These diffs are strong. I only broke one axle in about 4 or 5 years of hillclimbing and supersprints. Hillclimbs involve warm-up burnouts before each run and standing starts on sticky semi slicks. Mine was locked, so that might help if there's a weakness with spider gears, but welding normally makes life harder on the diff and axles.

Yes the tail shaft was balanced after being shortened saw it before and after. Was done buy 2 oldschool engineers in town here who are well known and respected.