I just bought a 1967 gran sport 400 and was wondering what tranny I have in it. Does anyone know what typically came in the gs400 from the factory? I'm pretty sure it has the original motor and trans.
It should certainly be an ST400. That was Buick's version of the THM400. On the passenger side of the transmission, there should be a small tag with identifying letters BA. The transmission should be a "Switch Pitch". The torque converter, input shaft, and front pump are different in a switch pitch transmission. The converter has 2 stall speeds, controlled electronically from the driver's side of the transmission. The THM350 has the vacuum modulator coming out the back of the transmission, parallel to the drive shaft, the THM400 has the vacuum modulator coming out of the side of the transmission, perpendicular to the drive shaft. The pan shape of the THM350 is square with a corner cut off. The Pan of a THM400 is shaped like the state of Texas. http://www.buickperformanceclub.com/switchpitch.htm
A 350 also has a kick down cable for passing gear, it's on the passenger side coming out near the front just above the pan. The 400 has an electronic kickdown, the wire terminals are on the drivers side. Bob H
