whereas most if not all "Series II" cars did not have the decal. Series II cars also received the lower seat cushion height/tilt feature that Series I cars lacked. Another distinctive exterior feature is the bright gold rotor-shaped 10th Anniversary Edition badge on the front fenders (yellow-gold on the Series II cars). A distinctive 10th Anniversary package feature is the all black leather interior (code D7), which included not just the seats, but the door panel inserts as well and a leather-wrapped MOMO steering wheel (with 10th Anniversary Edition embossed horn button) and MOMO leather shift knob with integrated boot. All exterior glass is bronze tinted (specific in North America to only the 10th Anniversary), and the windshield was equipped with the embedded secondary antenna also found on some other select models with the upgraded stereo packages. Other 10th Anniversary Edition specific items were headlight washers (the only RX-7 in the US market that got this feature), glass breakage detectors added to the factory alarm system, 10th Anniversary Edition logoed floor mats, 10th Anniversary Edition embroidered front hood protector and accompanying front end mask (or "bra"), and an aluminum under pan. GTUs (1989–1990) In 1989, with the introduction of the facelifted FC RX-7, and to commemorate the RX-7s IMSA domination, Mazda introduced a limited model labeled the GTUs. Starting with the lightweight base model, which came with manual windows, no rear wiper, the sunroof and A/C was dealer optioned, the GTUs added items found on the Turbo model such as four-piston front brakes, ventilated rear brake rotors, vehicle speed-sensing power steering, one-piece front chin spoiler, cloth-covered Turbo model seats, leather-wrapped steering wheel, 16-inch wheels, 205/55VR tyres, and a GTUs-only 4.300 viscous-type limited-slip differential (all other FC LSD's were 4.100). This allowed quicker acceleration from the naturally aspirated 13B. It was rumoured that Mazda built 100 cars in 1989–1990. There have not been 100 of these models found and registered. The only way to verify the GTUs model is through the door ID tag and firewall VIN. It is the only model with turbo ID tags and a non turbo VIN. Third generation (FD3S) The third generation RX-7, FD (chassis code FD3S for Japan and JM1FD for the North America), featured an updated body design. The 13B-REW was the first-ever mass-produced sequential twin-turbocharger system to be exported from Japan, boosting power to in 1992 and finally by the time production ended