AMC 258/4.2L Engine, Build Date 1/11/79 Heavy Duty Version w/ 1/2" Head Bolts and 12-counterweight crankshaft. This a Rebuildable Core. For Jeep CJ-7, CJ-6, CJ-5, 87'-90' YJ Wrangler, and Scrambler/CJ-8. AS IS, CASH ONLY! Call or Text...

Note: The AMC 258 engine came with a 12-counterweight crankshaft until 1981, when it was changed to a 4-counterweight design. The change was part of a weight reduction program that also included an aluminum intake manifold and plastic rocker arm cover. The new design saved around 20 pounds (9.1 kg). The AMC 258 was a 258 cubic inch (4.2 L) straight-6 engine that was produced from 1971 to 1990. It was known for being reliable, inexpensive, and torquey.