Need a tranny number decoded!?! Quickyl!
The identification numbers are 7 digits so I assume it's the 1st 7 digits of your posted # which is 4023814 but that # doesn't come up. The #'s jump from 3898869 right to 4028405. If by chance that 3 is an really an 8 (4028814) it's a 1978 904 that was used behind a 318
Here's a link to the only web page I know that has i.d. #'s
http://mymopar.com/downloads/transguide.pdf
You can bookmark it for future reference.