sheesh which felpro 1 piece oil pan gasket do I need?

[weider1717]

truck is an 87 4x4 350.

dip stick is passenger side and it looks like by reaching I need the "thick" gasket. I went to order my gaskets and saw they have one for a 1 piece or a 2 piece rear main seal.

what would my truck have came stock with? I need to know this before I order this gasket a long with all the others I will be needing. I take it order the 1 piece rubber oil pan gasket from felpro with a "steel core"?

thanks