Is the rear main seal in a 1994 Chevy 350 a 1 PC or 2 PC?

That would be a 1 piece solid round rear main seal.
No need to remove oil pan on that deal. You must either pull the engine are transmission to replace the seal. One are the other your choice. That seal slides over the back of the crankshaft, And it will pop right out no problem. Just alot of work to get to it.