how do you tell if you have 1 piece or 2 piece rear main seal. the engine has the dip stick on the passenger side. reason for asking it i am looking for an aluminum oil pan and they list two for passengerside dip stick one is for 1pc rms and the other is for 2pc

 

85 or newer should be 1 piece. If you look behind the flexplate there is a big aluminum plate that holds the seal on a one piece. 2 piece don't.