I've got a 1984 2wd ranger v6 5 speed and would like to convert to an automatic. Will a c3, c4, c5 and a4ld all hook up to my 2.8 without mods? Thanks.

 

Welcome to the forum

All engines have a specific bolt pattern for attaching a transmission's bell housing
Automatics have bell housings that can be removed and replaced to match the engines bolt pattern but that does require opening up the transmission and re-installation of the front pump parts, so not "simple" swap

Transmission from a 2.8l V6(your 1984 Ranger V6) which would be a C3 or C5, will bolt to your 2.8l V6
C4 wouldn't have correct bolt pattern

A4LD 1985-1987 could be used, 4 speed, but it's main advantage was TCC solenoid which you couldn't use in your 1984, but you would still have overdrive available
You would get this from a 2.9l V6 engine only, so it could bolt to your 2.8l V6, but 1988-1994 A4LD will not work in your 1984, as it required computer control to shift to overdrive