91 ford ranger 4liter The starter was bad the alt was bad and the battery was bad replaced them all truck runs but drains the battery over night Short Where?

sounds like to me the voltage regulator is bad.
if it is mounted on the fire wall replace it could possible short all of that again

In that year & size engine, the VR is probably integral to the alternator, that is, the alternator & VR is usually changed as an assembly.

The battery ground cable may be bad. The cable runs along the frame on the

passenger side. My '90 Ranger 4.0 had the same problem, found the cable was corroded/frayed at a clamp in the fender area. Replaced the cable, no more battery drain. FYI, NAPA was the only parts store that carried the correct cable at the time I replaced it.