904 output seal

[jjanack]

After far too long, I'm diving into fixing my puking transmission. Output seal boot sliced open, pretty easy diagnosis even for me. Problem arises as I get the new seal to press into the case, and won't even rest in the lip. A904 transmission I believe to be original to the 72 swinger original slant six car. The new seal is bigger, and the boot is shaped slightly different. tried all the parts shops, rockauto, napa, AZ, OReilly. Everything listed for the 904 is that slightly bigger seal. Am I missing something? Or off chance the trans isn't true to the car, would another generation be the key?

 

[Duster346]

Does the OD of the seal measure 2.38"?
I have a booted one.. or several non-booted ones.

 

[66Valiant528]

Get the PK number off the side of the trans pan rail above the neutral safety switch and contact someone with a mopar parts catalog. A lot of dealers don't have the old catalogs anymore. Get the oem number which will probably superceded about 15 times and get the latest number. Cross at any auto parts place and see what you get. Looks like you are getting a 727 seal You may have a different tail shaft on the trans as well. No numbers on the old seal?

 

[Syleng1]

I agree it looks like. 727 seal.

May have been just a bad packaging. I spoke to a guy at rock auto about a year ago and he said people return parts that were different but as long as it looks the same, they restock it and give them their money back.
Syleng1

 

[lkopaska]

There are two different rear seals for 904 trans , pre 72 and post 72 the original seal for pre 72 is a smaller out side diameter than the post 72.
pre 72 seal is getting harder to locate as most parts stores don't have the early listing and usually have to order it in.

Early national # 8935s

Lon

 

[Murray]

Replace the bushing also.