Is there any issues in using a long tailshaft th400 in a 70 cutlass? I know they came with the short version. I have to get a new tailshaft anyway. Just curious why they made 2 versions of the th400.

 

The long output shaft was used in longer wheelbase cars. The biggest issue I can see trying to use a long output shaft in a car is possible driveshaft operating angle might be excessive, and possible vibration. If the extension housing will clear the floorboard, the angles are acceptable, and you can have adrivewhaft built I see know reason not the use it. One advantage I can see is if the driveshaft breaks in a racing environment the shrapnel will be behind you.

 

Some long tail shafts didn't have the provision for the speedo cable. It went to the front wheel hub. Check for that.

 

Correct, but only on the 1965-70 full size cars. Olds also used the long tail TH400 in the Vista, again due to the long wheelbase. Be careful that some of these long tail transmissions from the 1968-69 timeframe are actually light duty TH375 versions. Those were used behind the 350 in Vistas and D88s.