Not super loud, but noticeable. Sounds like a piece of sheet metal dragging on the pavement, and only heard while under 20mph, completely goes away when drifting along in neutral.

Eliminated brakes and bearings and the diff (well, it has lube if nothing else). Driveshaft support bearing? U-Joint? Afaik nobody has lubed either.

If the rasp sounds maybe a bit like a rattle, then check if the bolt in the bracket holding the exhaust onto the gearbox is still tight.

Check for loose heat shields in the muffler area capable of rattling or touching the drive shaft when there's no torque, also just for the heck of it a loose exhaust manifold heat shield above the oil filter and as well make sure there's no gravel caught in the rear brake dust shields.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Ah, yeah, the first one wouldn't be seen easily when it's on jackstands, will do; second one is a no, banged on it pretty good recently; brakes I think might need another look since I just popped the pads in without pulling the rotor off. Thanks!

Also check internal hand brake mechanism. Axle safety strap touching tyre also worth a look.

Second suggestion to look behind the rotor, must do, probably couldn't hurt to put new shoes and hardware in there anyway. Thanks!

Axle safety strap might be there as a retro-resto-rally-mod -- it's a 1991!