1987 Chevy S-10 oil pump

Its been a while with this vehicle-if the new oil pump comes with the gasket use it-otherwise you go as is-

If it sucks air instead of oil

If, for any reason, the oil pump can't deliver its normal dose of oil, it's bad news for the engine. An oil pump failure is just as bad as cardiac arrest because the results are almost always fatal. Loss of oil pressure means loss of the protective oil film between the bearings and their journals. With no oil to keep the surfaces apart, the bearings wipe and fail.