July 5 2016, Houston service center at 3750 Westchase, Roadster # 1125 comes in shop for minor repairs and complaint of noise coming from rear of Roadster. This noise was not detected while sporting the Yokohama brand tires due to excessive tire noise, but when I switched to Michelin Pilot SS tires on the rear ( a much quieter tire), I began to hear a noise from the rear of the Roadster. My concern was a motor bearing noise. Not so. Tesla engineers in Cali. requested sound files from the service center first, in an attempt to analyze the problem. Next the Tesla engineers requested the motor be pulled and inspected for metal shavings. Non found. The engineers have determined that the Borg Warner transmission was the source of the noise and therefore Tesla is replacing it with the Last known transmission available ( in stock ) for the Tesla Roadster and known to Borg Warner. At one point, it was in route, and then a week later its status was unknown to parts dept., there was a possibility it no longer existed. July 28,2016, according to Tesla rep., Borg Warner would have to manufacture one. Aug.1,2016, transmission has been found and is once again in route to Houston and #1125 for installation. The Tesla reps in the Houston service center have bent over backwards to keep me informed and updated as events transpired. This service center has a great team effort, from the service manger and techs, to the service reps. upfront.