If it's original and in a C-30 is is "probably" a 292 4.8 liter. Both the 230 and 250 and 292 have the same bore, only the stroke is different. Also look for the numbers stamped at the distributor pad which indicate the trim of the engine. All 194, 215, 230, and 250 egines were the same physical size and the 292 is taller to accomodate the longer stroke crankshaft. The 194 was not used in trucks and the 215 was a Pontiac engine and the 230 and 250's were used in pickups so the likelyhood is the 292 CID. Very torquey engine.
