by Simon » Tue Oct 23, 2018 2:12 pm
Could have been either the stock half-width brake or the -54R road race. Suggest you post your VIN to the gents on the XR750 page on Facebook and they may even be able to tell you how it left the factory. This includes items like shocks, and other rare aluminium parts like fork caps, top fork clamp, and foot rests, etc. Parts books in the other sections of this site may help pinpoint the years.
I hope for your sake it was the half=width 1952-63 brake, or you've just added a couple of grand to the project...if you're restoring to original.
You should post this in the race section for maximum viewing/excitement perhaps.
I'm piecing together a 61 so we are probably in a similar boat!