And were there different Buster version built specific for the different big box models (A4000D/T, A3000D/T, A2000)?
The Super Busters (9 and 11) are only for 3000(T) and 4000(T) with ZIII. I believe there is 2 different versions of the Buster 9. One is for 3000 and one for 4000 although I don't know how much difference there is. There is only 1 universal Buster 11 as far as I know.
Are they truly meant to be interchangeable?
The Buster 11 is. It contains "fixes" for the 3000 that makes it more stable so it's definitely made for the 3000 too. I have used it for the 3000 and found it to be very stable and a good upgrade (allows for faster ZIII transfers).
Ask all this cause I need to know what I'm looking for. I'd like to find a Buster v9 - seems to be the choice chip, any leads?
You don't need the Buster 9 for a 3000. The Buster 11 is what you want with Deneb. Some 4000 owners need the Buster 9 with a Deneb. This is because the Buster 11 only supports 1 bus master and a 4000 with 4091, Fastlane, or 4000T SCSI have a problem because of this. The Buster 9 may not work properly in a 3000.
