I think the main issue is with people using RB26 ATI balancers, the 25 pump seems to sit slightly differently to the 26 pumps.
i.e. I have an R32 RB25DE head and RB20 ancillaries, using an RB26 ATI balancer with RB26 pump/bracket. My mates 25t/30 with the same balancer, his 25 pump didn't line up.