904's Keep Failing on 67 Motor

540slant6 said
So I have a 67 spec forged crank 318 in my Duster with a 67 spec 904 Auto. However, the motor came from a Sattelite that had a 727. So I changed the flex plate and have now destroyed 2 904's. The first trans broke off the convertor shaft clean at the welds. The second one is now puking fluid out the front and is doing the same thing.

My theory is that the 67 motor crank is only drilled for the larger 727 convertor snout. So the smaller 904 snout is walking in the crank and destroying the 904 sized convertors? Meaning that the 67 crank is drilled larger than the 904 convertor snout. I know that 67 is a weird transition year so any input is greatly appreciated.

I'm at my wits end and running out of money......

I believe you are correct. The pilot on the 67 crankshaft is larger. I'm not sure what year 904 converter you are using but if it an early one the snout is the small diameter. They make a bushing that presses onto the small snout converters. If you are getting a new converter just get the one with the larger snout. I believe 68-72 904 converters used the large snout. Hope this helps !