Well, I guess I had a more practical solution than some that this thread provoked! Let's try another tact: I am really glad to find I can use the ST-251 in my DEC Pro 380 instead of the Quantum Q540, since the later drive is rarer, older, and perhaps (in my experience) not too reliable. And has a smaller capacity, of course, and is a full-height drive. But now I have just one working 251 plus the one that sounds like a helicopter taking off, and another one that seems to work but that has ? ? ? written all over it. I can try to dig up some more 251s, but I got some remarks saying it wasn't too reliable a drive, either. Is there a better drive (MFM) with equivalent geometry? (820 cyls, 6 hds, 17 sec) or maybe with 6+ heads and 820+ cylinders (that might work, too?). Half-height would be nice, like the 251, because if I ever get another HD controller card, I can put two drives in my Pro 380 (only one drive per controller card, and supposedly only one per Pro chassis, but the 251 probably uses a lot less power than the Q540, so two drives should be OK). Thanks, Dave PG Manney wrote: