Recently I've been playing with an older Mamiya m645 I picked up some time ago. Mine predates the 1000s.
It came with a CdS prism (standard angle). Was there ever a 45-degree angle prism like with the Hasselblad or Kiev 88? I see there is a 90-degree adapter for the prisms as well as a differently-metered prism (standard angle) and a WLF.
My searches so far have come up empty, so I suspect the answer is no, but I thought I'd check with more knowledgeable m645 users first.