http://lowendmac.com/sable/07/mac-drive-setup-patch.html says it all: any 50-pin scsi drive (though best if >2GB for use in a 550) can be used in principle.
However, without a third party utility or a patched version of HD Setup, only drives with Apple Roms can be used - in other words, drives with an Apple marked on them (or that came from an Apple machine). Thus the patch is a good thing to have, or something like Silverlining if you want to go third party, because it widens the possibilities to include the sort of drives 30pin found in that IBM server.
Whatever CD drive you use will require the requisite Extension. As far as I know, a high speed scsi CD like the ones that came in late Beiges like the 9600 will not work with the standard 1st or 2nd generation Extension provided by a stock installation of 7.1 or 7.5, but a CD 300 or 600 should work just fine. You could try popping the extension from 8.1, say, into your 7.1 system folder and see what happens, mind you.... A third party CD Extension would also widen the selection again: there was FWB software that did this, as I recall. Maybe the Toast extension would do the trick, too.
The other limitation I can think of concerns whether the drive (and corresponding Bezel) presently in the 550 in question is tray-loaded or caddy-loaded, because this would limit your choices of replacement.
I'd maybe try disassembly, cleaning and lubrication if the CD drive is noisy — what's there to lose but an hour, during which you just might learn something about the machine and the mechanism?
However, without a third party utility or a patched version of HD Setup, only drives with Apple Roms can be used - in other words, drives with an Apple marked on them (or that came from an Apple machine). Thus the patch is a good thing to have, or something like Silverlining if you want to go third party, because it widens the possibilities to include the sort of drives 30pin found in that IBM server.
Whatever CD drive you use will require the requisite Extension. As far as I know, a high speed scsi CD like the ones that came in late Beiges like the 9600 will not work with the standard 1st or 2nd generation Extension provided by a stock installation of 7.1 or 7.5, but a CD 300 or 600 should work just fine. You could try popping the extension from 8.1, say, into your 7.1 system folder and see what happens, mind you.... A third party CD Extension would also widen the selection again: there was FWB software that did this, as I recall. Maybe the Toast extension would do the trick, too.
The other limitation I can think of concerns whether the drive (and corresponding Bezel) presently in the 550 in question is tray-loaded or caddy-loaded, because this would limit your choices of replacement.
I'd maybe try disassembly, cleaning and lubrication if the CD drive is noisy — what's there to lose but an hour, during which you just might learn something about the machine and the mechanism?