Indigo R3000 was VME-based, a derivative of the 4D/35 and firends Indigo R4xxx was a completely different architecture shared with the later SGI Indy Both had

Indigo R3000 was VME-based, a derivative of the 4D/35 and firends Indigo R4xxx was a completely different architecture shared with the later SGI Indy Both had GIO32 slots Same case, same slots, totally different architectures inside