904 Tail Shaft Seal Selection?
This is really of little importance but the Transtar transmission catalog shows 12925B as 1966-1972: 2.254" OD. with dust boot.
Evan Dutch can ignore the following statement because it relates to the larger seal that was used on 904's starting in 1973.
Chrysler part number 3515384 with dust boot was used from 1973 thru 1982 on the 904 transmissions.
In 1983 Chrysler discontinued that number and replaced it with #4058047 which had no dust boot. Don't have any idea why they eliminated the dust boot but that's what you got at the dealership from 1983 on.
Aftermarket seals that were made starting in 1983 were available with or without the dust boot.