How Do I Identify Manual Transmissions on Chevy 1988 -1992 Trucks?by Floyd Drake III
The five transmissions installed on 1988 to 1992 Chevrolet trucks, according to Drivetrain.com, were the Borg-Warner T5, the Getrag, Muncie or New Venture models HM290, 5LM60 and NV3500 and the New Venture NV4500. The NV4500 appeared on 1992 full-sized trucks only. Locating the manufacturer's tag, if present, is the easiest form of identification for all models, with visual methods reserved for general identification. Positive identification of these transmissions is accomplished through internal methods, especially when differentiating the HM290, 5LM60 and NV3500 models. Since the differences between these three are internal, removing the transmission is necessary.
Look for the manufacturer's tag, usually attached to a bolt on the transmission extension housing. This tag identifies the manufacturer and the model transmission. Borg-Warner transmission model numbers begin with "1352."
Inspect the transmission for visual characteristics. According to Motivegear's Domestic Truck Transmission Identification Guide, Borg Warner T5 transmissions are all-aluminum, five-speed, top-loading transmissions with the bell housing not integral to the unit. On HM290/5LM60/NV3500 transmissions, the bell housing is integral to the to the aluminum-casting and the case has a waffle pattern after the bell housing, towards the rear of the vehicle. The NV4500 is a top-loading, cast-iron, heavy-duty transmission with an aluminum shift cover. Weighing around 200 pounds, the NV4500 may have a warning label located on the case designating the use of Castrol Syntorque fluid only. Top-loading transmissions have an access plate bolted to the top of the unit.
Identify the HM290/5LM60/NV3500 transmission differences. Since these differences are internal, including gear ratio and bearing specifics, the transmission has be torn down for proper identification. Each of these models were manufactured by a different company and each employed its own design changes. One difference that separates the HM290 and 5LM60 from the NV3500 is the NV3500 has one shift rail, as opposed to the four on the HM290/5LM60. Refer to a listing, such as the one found on Drivetrain.com, for proper identification specifics.
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