Hi, Erol.
I am using a Quantum Fireball on my Amiga and have never been able to find an adaptor to fit any LED to the drive access pins. They're just too tiny.
I have found a sort of solution, though. EMail me at
billsey@earthlink.net and I'll see if I can send over the slightly modified DriveLight utility that I use on my workbench. It's not a perfect solution, but you can at least tell whether the device driver in question is being accessed.
The usage is simple. You can monitor up to four different devices (such as your RAD and your SCSI chain) by naming the appropriate device driver in the commandline. The one I have ready is modified so that it won't totally block the title bar text on the Workbench but will appear about halfway down the title bar.