Glen, that engine was manufactured on 30 June 1977, so the mower was probably made later the same year or early in 1978. The engine is 13 cubic inches (213 cc), first design series, vertical crankshaft, plain main bearings, rewind starter.

This is the engine Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=msotJO-K_ny7tH217FzoPu

This is the engine's Illustrated Parts List:
http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=Z6kpuBVJ1DajI