JC, googled it came up as 81/82 XR I think, was pretty easy to find, but they are rare or non existent in the UK
Brent, I'm having trouble finding out the same info for IT/YZ triples. I can't be sure which models were 38mm. They went from 36 through to 43. I also want to find out the standard YZ/IT gap between top and bottom triples. DR400s are I think longer in the head tube than XTs.
The RMC swingarm is dimensionally the same widths and length as a 175 PE, slightly wider without the rear wheel adjusters
The shock pivots are further back, better for a DR. I checked back through the suzy forum and sure enough someone else had said the RMC was the best DR fit.
Oldfart cautioned as to a the pivot housing tube being well distorted. It was, so I returned them. That or get a new pivot tube, but it looked like a money pit.
I'd like the White Bros or similar swingarm. But they couldn't have made many.