Ah was that it. I thought the 50 denoted the 2-cpu version, the 00 the single cpu and that the 83xx was the faster version? of the 82xx I always had trouble with this too, but here's the scoop - VAX-8200 - 1x KA820 (T1001-00) CPU VAX-8250 - 1x KA825 (T1001-YA) CPU VAX-8300 - 2x KA820 CPU VAX-8350 - 2x KA825 CPU The model numbers corresponded to the CPU cards (e.g. KA820 -> 8200, KA825 -> 8250) ... The KA825 (T1001-YA) was simply a faster version (6.25MHz vs 5MHz) of the same KA820. Bob