To identify different Chevy transmissions, check the transmission pan size or the identification number marked on the casing, if the transmission of the vehicle is automatic. In vehicles with manual transmissions, check the number of bolts on the cover of the transmission.
In Chevy vehicles with automatic transmissions, park the automobile on a flat surface, engage the parking brake fully and access the vehicle from underneath to check if the transmission pan is secured beneath the transmission with bolts.
If the pan appears shallow and nearly square, the transmission model is THM700-R4. The transmission model of a pan that is square and shallow, but with a missing back corner, is THM350. If the pan is marked as 375-THM, then the model is THM375.
The pan of the THM200-R4 transmission model is longer and deeper, and it has a shallower pan near the vehicle's rear side. If the pan is long and uniformly deep throughout, the transmission model is THM400, which is found generally on bigger Chevy automobiles.
If using the source serial or identification number normally marked on the transmission towards the driver's side, compare it with a transmission type list that is based on the Regular Production Option number.
In Chevy vehicles with manual transmissions, access the vehicle's underside from its front, and locate the cover of the transmission with its housing located at its back toward the vehicle's rear side. Transmission covers with nine bolts indicate that the model is a Borg Warner.
Seven-bolt covers with a reverse-shift lever at the front are the Saginow models. If the lever is not visible, but the cover has seven bolts, the transmission model is Muncie, which is commonly found in heavy vehicles.