The Sd.Kfz.251/21 Ausf.D Schützenpanzerwagen “Drilling” which had a triple-mount (“Drilling” in German means “triple”) of MG151 auto-cannons on a converted 15mm Naval pedestal usually used for a quad MG34/42 mounting; early version being Rheinmetall-Borsig MG151/15 mm cannon (second photo), later being Rheinmetall-Borsig MG151/20 mm Luftwaffe cannon(third photo).
This was posted in relation to this post. (Sorry Lux, I had to go full on Nerd so folks could get an idea bout that picture.)