This engine is out of a 1991 s10 it is not a vortec the manuel for that year says 160 hp stock but that is with the computor and rev limitor and tbi.I have not been inside of this engine it has 56000 miles and is reaiy in good shape. I didn't know anyone made after market heads fir it that is VERY interesting. I like a lite engine keep the overall weight down and make a real sleeper of it