The Turbo 400 is a heavy duty Chevy 3 speed automatic
transmissions. They have an aluminum case and two variations in
output. Some Turbo 400s used in Jeeps were built to bolt to the Dana
20 transfer case and some were built to bolt to the BW 13-39 "Quadra-Trac"
transfer case used during the 70s. The versions of the Turbo 400 are
not compatible. The factory adapter used on the Dana 20 version of the
Turbo 400 is light and prone to failure. The drive gear used with the
Turbo 400 to Dana 20 is not 6 spline, so you cannot bolt a Dana 18 to
this transmission. The case is 24 1/2" long and 13 bolts hold in the
The TH 400 was used in CJs with the BW 13-39 transfer case from
1976-1979. The TH 400 was used in full sized Jeeps (SJs and J series
pickups) from the late 60s until 1979. The TH 400s used in CJs and
later SJ had the AMC engine bolt pattern. In the late 60s the TH400
was used in SJs with the Buick 350, so it had the BOP/BOC (Buick,
Olds, Pontiac, Cadilac) pattern. Some early TH 400s with the AMC
engines used an engine to transmission adapter.
Side view of TH400 transmission.
Back view of TH400 transmission.
Front view of TH400 transmission.