Interesting discussion so lets continue.
It's true that National made the seals for Chrysler.
The 904's from 1960 till 1965 had no dust boot.
Let's start with what was available from the Chrysler dealer.
If you purchased seal number 2400163 from the dealer from 66 thru 72, it came with a boot. Non booted seals from 66 to 72 could not be purchased from the Chrysler dealer.
Handled many of the old brown boxes used in the sixties with the number 2400163 which contained the booted seal. The aftermarket produced seals with and without the boot.
#12925B seal with boot
#12925c seal without boot
Most transmission shops got there parts from transmission distributors with there own part numbers.
You would think that most people restoring Mopars would prefer to use Chrysler labeled parts when possible.