Was it Yamaha? For some reason I thought the engines were built by Mercury Marine. I must be getting old and forgetful.
EDIT:
A little googling revealed that Mercury Marine produced engines for the Gen 4 Corvette ZR1. That must be what I was thinking of.
Mercury marine were basically GM motors. The 4.3 6 cyl that was absolutely bullet proof in GM trucks was basically the 160 hp Mercruiser engine. Some change’s obviously for marine application but not much. I could run around on Lake Erie and upper Niagara River all day at 3500-4000 RPM. So 1500-2000 was no problem going down Highway in a 1500.