OK, so here is my problem (and I have never really had a problem with SCSI before).
In order to get my Quadra 950 set up with OS 8.1, I first installed it onto an external SCSI HD using my 6500 (selecting OS 8.1 for any computer). Then I booted the Quadra from the external HD and repeated the game on the internal HD (this time selecting just "OS for this computer").
I also have an external SCSI Zip drive hooked up through the external HD and it takes care of termination of the external SCSI bus (SCSI IDs are different). The internal SCSI bus has the HD, a CD-ROM and is terminated with a small connector (not sure though if it is needed).
So here is the problem. When I boot from the external HD, the Quadra recognizes the Zip drive with no problem (it mounts Zip disks). When I boot from the internal HD, no mounting (the Zip drive clearly does not even attempt to read anything from the disk). I haven't checked the SCSI bus yet to see if the Zip is found, but for some reason I doubt it will (I will check soon).
Any idea why this is? Is it possible that the termination on the Zip drive doesn't work and only when the boot disk is on the same bus it is "seen".
ps. I installed the PowerPC card into the Quadra and it now has the nicest turn on chime that I have ever heard. Does anyone know how that works? Does the PowerPC card take over the PRAM (or wherever the chime is stored)? It really is a cool chime.