904 transmission rear seal

[Cardinge72]

Ok I'm new to this so bear with me I have a 1972 duster with a 340. I bought the car which was restored six years ago but now have a rear transmission seal leak. So I went to change it and the seal listed is too big compared to the one I pulled out. How can I find out what this transmission came out of this car is a clone and originally a slat six car. It seems the tail shaft is much smaller than what's listed for the duster

 

[RedFish]

If the parts clerk looked up 72 340 car he may have found 727 trans instead of 904. Maybe have him look up 72 slant 6 and see what you get
If If If, Since we know this is a piece work drive line, If drive shaft balance and/or yoke insertion depth aren't proper, the tail shaft bushing may be the root cause of leak. A new seal alone wouldn't fix it.

 

[mguner]

And there are a couple of different sized (O.D.)output seals for the 904 based transmission as well.

Housing bore 2.372 uses National# 2506
Housing bore 2.249-2.25 uses National # 8935S

Both of these are the boot type seal.