Both the TH350 and TH400 have a similar look. Using the pan bolt pattern is the easiest way to identify the TH400.

Th350 has the vacuum modulator in the back, and the TH400 keeps it on the side. The TH350 uses a mechanical linkage that attaches to the carburetor. The TH400 uses an electronic kick-down mechanism, which means that there will be an electric plug on it. Since these are the two most common GM automatic transmissions of the latter half of the last century it’s very important that you figure out which is which. If you count 13 you are almost home free, but the Th350 also has 13. There are 13 bolts on the pan underneath the transmission. Since it’s not very likely that you are going to run into a lineup of automatic transmissions being the biggest isn’t going to be very helpful. It would be far and away the largest transmission there. If it was lined up with a 200-4R, TH350, or 4L60E it would be easy to identify a TH400. If you were to line up every automatic transmission that GM ever produced, you’d be hard pressed to find one that is larger than the turbo 400. It’ll have The TH475 was used in heavy duty trucks in the 1970’s, and can handle a lot of power. If you are looking to purchase a TH400 avoid it. It was modified to fit the TH350 driveshaft yolk. The Th375 was manufactured for cars with low horespower engines in the 1970’s. There are were a few one of versions of the Turbo 400 as well. It also does not use a locking torque converter. It uses the B-O-P bellhousing bolt pattern which makes it compatible with nearly any GM engine. This is because the TH400 was never designed to communicate with the CPU of the vehicle/The 3L80 was the last non overdrive transmission used by GM in regular production trucks and vans. Note that unlike all the other GM transmissions of the time there was no E at the end of the nomenclature. 3L80 stands for three gears, longitudinal mount (rear wheel drive), and the 80 signifies that it can handle 8000 lbs. There is no difference other than the name. In the early 90’s GM rebranded all of their transmissions, They created a standardized naming system across their product line, and changed the name of the TH400 to 3L80.

It’s controlled by a vacuum module and kickdown switch Outer Case Material: Aluminum, fused with bellhousing Production: 1964 (for 65 model years) through 1990ĭifferent applications had different lengths due to different tail shafts/transfer cases.

Turbo 400 TH400 Specs Manufacturer: General Motors The TH400 has appeared in Jaguars, Hummers, Ferrari’s, and many more. More than almost any transmission ever made, it has found its way into a wide variety of vehicles outside of the GM family. The TH400 came in two wheel drive and four wheel drive vehicles, passenger cars and heavy duty trucks, as well as GM vehicles and those made by other manufacturers. It was introduced for the 1965 model year and made its debut in Cadillacs, and is respected for its durability and adaptability. The TH400 is an aluminum cased three speed automatic transmission that was produced by GM.

Th400 transmission