used with high-power applications — primarily the Buick Grand National and the 1989 Pontiac Firebird Trans Am Indy 500 Pace cars. The 200-4R was configured with several different torque converters depending on the vehicle application. However, this transmission was also prone to failure (especially in D-body Cadillacs) and received improvements during its production run. The first improvement came in 1984 with a change of a servo piston from using split Teflon sealing rings to a servo using lip seals. A real problem area was the stamped-steel drive shell, which would strip out, losing reverse. With the 1985 production run, GM started installing a hardened drive shell, but continued to supply the original style until parts inventories were exhausted. Another major problem area was the pump assembly. The pump halves were made of cast aluminum and the pumps themselves were made of made up of steel segments like a power steering pump. There was a steel hub and variable ratio outer ring. Because the pump segments traveled in an eccentric circle, guide rings were necessary on top and bottom of the center hub. These rings would break and cause the pump to stop pumping, as well as damaging the aluminum housings. The aftermarket came with hardened rings which solved this problem. Unlike the 700R4, most 200-4Rs have a multicase bellhousing for use with Chevrolet, Buick/Olds/Pontiac (BOP), and Cadillac engines. However, 200-4Rs share mounting locations with the TH-400. Since the external dimensions are longer than the TH-350 but the drive shaft yoke spline count/diameter was the same, the 200-4Rs can be swapped in place of TH-350s, with the shortening of the drive shaft, in older vehicles to provide an overdrive gear. Early models had a "PRND321" shift indicator, while later models used "PRN(D)D21," with the left D identified as the overdrive gear by a square or oval ring. The THM200-4R can be found in the following vehicles: 1981–90 B-bodies 1981–84 C-bodies 1983–88 G-bodies 1985–90 D-bodies 1989 Pontiac Firebird Trans Am Indy Pace car (with the turbocharged LD5 Buick V6 and a turbocharger) The THM200-4R was phased out after 1990; its final usage was in the GM B-body vehicles. THM700R4 / 4L60 / 4L60E / 4L65E / 4L70E The four-speed Turbo Hydra-Matic 700R4 was introduced for the 1982 model year for use in Chevrolet/GMC vehicles. In 1990, the Turbo Hydra-Matic 700R4 was renamed the 4L60. Under the new designation, the "4" stands for