R+D stands for Roger the Dodger (the company logo lookes like "RTD").

I also had an R+D gearbox, a 5 speed syncro based gearkit for the MT75, cost £3k, took them 2.5 months to build it when he told me it would be done in 2 weeks (siad all the bits were in stock), biggest pile of shite i have ever had the misfortune of using, it went back to them twice in the space of 6 months as it was binding (car would lunge forward when starting the car in neutral!), and crunched like hell on gearchanges, and the customer service is just non-exstant, you can't even get to talk to him 99% of the time (hence the nickname). I would NEVER use R+D for ANYTHING, EVER!