International had no hand in developing the Nash! Sixes. Nor did theyhave a hand in the amc v8. International did buy and use the 258 six during it's death in the light truck market. I just finished today as a matter of fact. A rebuild on a 1989 258. These are very tough old sixes. Can take a ton of abuse. Can be built with a mix of 4.0 and 4.2 parts to make 350hp. Even now I rebuild a few dozen 258 and 4.0 liter sixes per year. Last fall I built a supercharged 4.0 that's pumping 400hp. It's in a jeep tj. And is a beast. My one and only new rig. Bought in 1988. Is a wrangler. With s 258. 5 speed . Swapped in dana 44 rear. Never rebuilt. 389,000 miles. Best straight 6 ever built.
