Yes it is a R4 made by GM and was manufactured at their Harrison plant in Ohio(Plant has since been sold). Also used in all GM cars and pickups at one time or another for the v-8s.. the American version as I understand it, is made 180 degrees opposite the MB version as the American version sits up near the top of the v-8 and the MB version is down at the bottom of the engine. I think the oil reservoir inside the American model is opposite the MB version. So if you use the American version the oil reservoir will be on top the AC compressor when used on a MB instead of on the bottom as needed for lubrication.. Maybe someone else has a different take as I have never really checked one against the other... jim16671836

__________________
James A. Harris