4 speed overdrive

[71RALLYEDART]

Can an early 80 s overdrive truck transmission's tail shaft be changed with a regular a body tail shaft to make the verdrive a direct bolt in

 

[mischiefdart]

Yes, you will need the mainshaft and the extension housing from an a/f body o/d trans.

 

[67Dart273]

Are you absolutely sure? I was under the impression that an OD shaft was smaller than a 4 speed?

 

[tamanko]

Just came across this thread. I have done this conversion. It turned out well and ended up with an all aluminum transmission.

 

[V-100]

Any difference in the strength of the cast iron over the aluminium? I've heard for instance, that the '76 F-body CI OD was the best one to get for an A-body conversion due to it being a more rigid housing, more bearing support/load capability.

 

[72bluNblu]

Are you absolutely sure? I was under the impression that an OD shaft was smaller than a 4 speed?

Sounds like the OP has an OD truck transmission and just wants to install an A/F body OD mainshaft and tail housing, that's a straight across swap, all you need is the tailshaft and shorter OD mainshaft.

You can even swap OD gearsets into regular cast iron 4 speed 833 housings, but you have to swap the entire gear set with the mainshaft. Or swap 4 speed 833 gearsets into an aluminum OD housing, but again, you have to swap the entire gear set. The mainshafts are a little different, so you can't put OD gears on a 4 speed mainshaft or 4 speed gears on an OD mainshaft, but you can swap the entire thing from case to case.

As far as durability, it is better to have the cast iron case. That's why Ma Mopar increased the size of the input bearing on the aluminum cases. In high horsepower, or high mileage cases the bearings/shafts can start to get loose in the case. You can also have the aluminum cases sleeved with steel bushings to help prevent/correct that.

 

[mischiefdart]

If you use the iron case it has to be for the larger "308" input shaft bearing. Most iron cases use the "307" bearing.