Help! Oil Leak..

[HotRod73]

I have a 73 Chevy C20 3/4 ton pickup. Has a 350 motor and is leaking. Its leaking by the flywheel cover, it has a hole in the bottom i guess to let oil drain, well its coming from there... its not leaking from behind my block i looked at the intake etc and no oil leak, its got to either be my oil pan gasket at the back, or a rear main seal, or both or i was told something about oil sending unit or something could be possibility? it isnt leaking a whole lot but its noticable on the ground and smells when truck is hot... what do you think it could be? i know my oil pan is leaking a tiny tiny bit around a few of my bolts could this be it? i havent taken my flywheel cover off to inspect but thats were the oil is dripping from.... if its my oil pan gasket, will i have to lift the motor to take the pan out or will it slide out without messing with lifting motor?