albertaboy, do you still have that pipe. It looks identical to the pipe on my 750, the plate at the back is long gone but it has the same step down weld where the muffler is attached and the mounting tab is the same. I'd love to see pics of yours from the front as well as the number of holes in the end plate of the baffle as well as a measurement from rivet to rivet, possibly from the end of the pipe to the mounting tab hole.
A PO had bbq painted it, last year I wire wheeled it back to bare chrome and the only ID mark I could find was the number 750 stamped into the muffler on the backside of the pipe near the mountin tab. Any chance you can take a coue more pics and a measurement or two?