Actually, only the 40X and 48X are 51mm deep. The 60 is the usual 34mm.

The nice thing about the depth figures on the 4ms Pods, though, is that when they say 34mm, they mean it. The power components are all hiding up under that rail area at the top, so there's no busboard, power supply, etc surprises that turn your 60mm deep cab into a 40mm deep cab. The only "extra" impediment would then be ribbons and making sure there's clearance for those.