leaking like a civ

I've got an '87 B2000 with only 66k miles but its leaking oil at about a quart a month and its getting worse. The truck does not smoke at all and there is no intermix. Has anybody had similar problems? Is there one specific gasket that tends to leak more than others? Has anybody had the major gaskets replaced and if so about how much were you charged? thanks

Clean the engine off with GUNK or kerosene.Park it over some newspaper so u can see where it is leaking.At the age of the truck ALL the gaskets are hard as bricks so there is no telling which one(s) are leaking. Prime suspect is valve cover gasket followed by front crank seal,followed by rear crank seal,followed by oil pan gasket.It all depends on where the oil is coming from.BJ