These are all internal drives, right? It sounds more like a SCSI problem than a Fastlane problem. You tried a drive with 50 pins and it worked fine, but all the drives you tried with adapters gave you trouble? I'm using an IBM 9GB 68pin drive with a 68->50 adapter, and a Seagate 4.3GB 50pin drive on my Fastlane. They are in an external case with an active terminator ending that chain. I have no internal devices and I'm using the passive terminators on the Fastlane to terminate that end of the chain. How much memory you have on the Fastlane isn't going to affect the SCSI.
I'd first double-check the SCSI termination and adapters. What kind of adapters were you using? Some of them have special requirements when you connect them, such as setting jumpers or terminating a certain way. If you have access to another computer with SCSI (not necessarily an Amiga), it wouldn't hurt to see if that computer can "see" the drives.
It's a wonderful thing when it works, and downright frustrating when it doesn't. Took me an age and a day my first go around, too. Once I got the termination right, everything was fine.
-David
