1982 inline 6 needing help on transmission identification

[Death_the_end]

Hi I recently purchased my 1982 mustang and it has transmission issues I have been trying to find out which transmission is currently have to get a replacement for and to see what I can replace it for as a pretty much direct swap. Any help would be awesome. I believe it’s a c4 but not sure how to find out for certain.

Thanks for any help

 

[General karthief]

Is the 'door tag' still visible on the drivers side dog leg? It will tell you what the factory,
Here's a post showing the look of each.

Automatic Transmission Identification Guide - FORDification.com