I am pretty sure (tho I've not looked at the manual) that MACH3 can provide a spindle speed display, but that wouldnt be on the machine... which would be nifty but not of any great value... finding an off the shelf panel mounted rev counter might be tricky, a quick google didnt reveal anything useful... whatever it is needs to be able to scale at 50:1. A simple PIC-based solution would be easy to implement tho...

That Texon is ugly, but easy to replicate... maybe I'll knock up a quick PIC design for it...