If you spend time researching GM Transmission Mounts Online with Various Forum Posts there is alot of Confusion what exact GM Used for Transmission Mounts Musclecars made from 1963-1974 & into the Disco Years to 1981 with the Firebird & Camaro.
The Early 1970-1/2 -1974 Pontiac Firebird Trans Ams & Camaro Z-28 all had the Turbo 400 Automatic Transmission or the Muncie 4-speed M20, M21, & M22 Manual Transmissions.
I own a 1970-1/2 Pontiac Trans Am RAIV Muncie 4-speed Musclecar. The Transmission Crossmember has the 2-bolt pattern TH400 style transmission Mount Pad. Used all GM Musclecars 1965-1974 with the Turbo 400. It takes the Shorter GM Trans Mount.
Energy Suspension # for the 1970-74 Pontiac Firebird & Trans Am Line with a Pontiac V8 is 3-1158G. It measures 1-5/8″ tall or 1.625″ inches.
1974 was the Last Year for the Turbo 400 transmission in the GM F-body line for Pontiac & Chevrolet. 1975 -1981 the Turbo 350 transmission was used because the TH400 would no longer fit beside the Huge pellet catalytic converter introduced to meet anti smog laws. These years used a Single stud transmission mount that had a Taller Height of 1-15/16″ or 1.9375″ inches. Same holds True for the Borg Warner Super T-10 transmission used in the 1975-81 F-body.
Energy Suspension Transmission Mount for 1975-81 F-body Pontiac is 3-1108G.
Keep in mind the that Pontiac V8 engine Firebird & Trans Am had unique Frame Bracket Mounts used for years 1970-71. Then 1972-74 style. And then for 1975-79 with the Pontiac 350 & 400 cubic V8. The Pontiac 301 & 265 V8 Firebirds & T/A had different engine Mounts yet.
And I recall that Pontiac Firebird & Trans Am 1970-74 had different part number steel trans cross members for the the TH 400 & for the Muncie 4- speed cars.
Start mixing up parts from cross over years & you will have driveline install issues & driveshaft Pinion Angle variations from factory Stock.
Review again :
Energy Suspension 3-1158G (Black Polyurethane) is for Turbo 400 & Muncie 4- speed stock Musclecars 1965-1974. Also fits 1963-64 Chevy Nova II V8.
Energy Suspension 3-1108G (Black Polyurethane) is for Turbo 350 & Borg Warner Super T-10 stock 1975-81 Pontiac Firebird & Chevy Camaro. With a Pontiac V8 or Chevrolet V8.
When in doubt you can double check measure your original factory transmission mount also.
Just 3/16″ or .3125″ inches difference between the GM TH400 & TH350 transmission mount heights but will change your transmission driveshaft rear differential pinion angles.
Brian R.
