There are only two A600 accelerators I know of, the Viper 620 and the Viper 630. You had the 630 one, I guess. You won't find the 620 these days, and even if you did, it still has the same weird "clip-over-the-68000" design and is really tight on space inside the A600 - in fact, being the forerunner of the 630, it wasn't designed as well and was prone to slipping off. It was a lot cooler but was half the speed of the 630.
I think there were no other A600 accelerators made. The A600 was not designed to be upgradable. The Viper 6x0 cards were pretty special.
