Hello, I have a couple of 3.09 first gear, overdrive, small mainshaft, in an aluminum housing transmissions. I also have a 3.09 first gear, overdrive, large mainshaft, cast iron housing, transmission and was wondering what these came in. Thanks

The difference between the small and large mainshaft is the diameter, they are both short tailstock, tc

Are you sure that the cast iron one is an od trans?? Yes they did make a few, they were either early model overdrives or were out of a truck/van. By "mainshaft", are you talking about the input shaft (where the clutch rides) or the output shaft?(where the driveshaft goes in??) AFAIK, all the input shafts on the OD trannys were the same, and the output shafts all took the larger 727 sized slip yoke, but there were long tail and short tail versions. Longtail OD would have originally been truck/van, and short tail would have been out of a car. The long tail would be the same length as the older B&E body non OD. The short tail would be the same length as a trans out of an A or F body. By the time that the OD trans came out I believe that auto trannys were "standard" in B bodies, (E bodys weren't being made any more) so any long tail would be a truck. By this time the only cars that you could get a stick in were A or F bodies. I have a long tail cast iron OD that came from a 78 van, and a short tail aluminum from a Volare. I am leaning towards putting the cast iron one into my car but not sure yet. (looking more for durability than lightest weight) For a daily driver the weight penalty wouldn't be enuf to be noticed at the gas pump,
but the cast iron case ones are less likely to wallow out the hole in the case where the countershaft rides.

I do not agree with that. The A833 I had out of a Volaré / Aspen used the same slip yoke as the A904 automatic in my Valiant. I even installed the OD trans in the Valiant in place of the original automatic and used the same drive shaft and yoke, no modifications anywhere.

I pulled a short tailshaft overdrive 833a out of a 75 Dart and put it into my 70 Dart. The case is cast iron, first gear is 3.09 and the yoke is the larger size. The 70 Dart has a 360, and did have a 727 auto. I had to lengthen the shaft to work, since the tail shaft on the 727 was longer than the 833, but I used the same yoke for the 833 that was in the 727. To get the longer length, I used an old 904 drive shaft, and installed the larger yoke. If I remember correctly, I had to shorten the 904 tranny shaft an inch or two. Not because of differences in the trannys, but because the rear is an 8 1/4" not the 7 1/4" that the 904 shaft was ahead of. It can get pretty confusing, and hard and fast rules will nearly always be wrong somewhere along the line. As soon as you think you know everything about something, especially Mopar, along comes an exception.

IIRC, some of the early OD trans' were cast iron housing.

There should be a stamping pad with the date code on them somewhere.

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