Had the p38 out for a long drive today. At one point in roadworks doing about 40mph I noticed a pretty worrying noise.

Sounded like a rubbing or scraping sound from the rear axle or something around there. Most noticeable when holding the throttle at cruise. Full over run or acceleration seemed to make it go away or at least become much less noticeable. At higher speeds I couldn't really hear it any more.

I also have a clonk noise when changing drive direction, eg shifting from reverse to drive, most noticeable at low speeds, which might be related?

Any ideas where I should be looking?

Clonk is likely to be wear in a diff unless it is a propshaft UJ on it's way out. In fact a UJ running dry could also give a scraping noise too. They aren't easy to check without disconnecting one end of the propshaft but if you try squirting grease into the nipple and it all squirts out again, that's a sure sign of wear.

check the obvious first brake pads then universals ?

brake pads i thought about at the time, gently touching the brakes didnt seem to alter the noise though, and braking harder it would go away.

I'll need to get underneath and check the propshafts i guess!

i'd go diff... spent ages messing around with mine and that's what it was - but yes, slack in drive train... so UJs also an (easier) option

I've suspected the rear diff for a while, when i got it, it was noisey on overrun at motorway speeds. That noise has either gone away or i've stopped noticing. I also changed the oil at one point and it was properly black and burnt looking, whereas the oil in the front diff looked nice and clean.

Still, investigation required. In particular the propshafts as if those fail it could get messy!