Appears to be a "B" body booster, with the rod that comes out the back end of the booster.
NOT A HEMI ONE, THOUGH.
Agreed, the B body rod measures about 3 1/2" to 4" in length, the C bodies are generally 6" in length in most common applications, but I have found some variations over the years, as I procured many dual diaphram bendix units from B/C vehicles for HEMI booster conversions in the past for customers vehicles
FYI: C bodie booster rods generally bolt right to the pedal, hence the need for a longer pushrod, B bodies employ the intermediate linkage pieces for most applications
