Can someone help, oil leak?

I have a 1994 chevy z71 with a sbc in it. I cant figure out where its leaking from. Its not the oil pan, oil sending unit, valve covers, and the oil filter is tight. It leaked a whole 5qt jug of Penzoil platinum out in 1 1/2 weeks . Does anyone know where the leak might be. I'll appreciate any advice, thanks.