RE: sick people in the world
The 4.2 and the 4.0 are basically the same engine with a different bore/stroke, for the most part. The longer stroke 258 is a low rpm, stump pulling machine. Maximum torque output happens almost as soon as it starts turning up. The 4.0 is a shorter stroke/ bigger bore combination that runs alot better in the mid-upper range, but reaches peak torque at quite a bit higher rpm, which isn't the best thing for slow speed offroading. The 4.0 feels more sporty, especially with a manual transmission and some good gears.
The neat thing about a 258 is that they are pretty tame in factory form, but it can be turned into a little monster with some simple and common mods. Horsepower can be brought up to and beyond the level of an HO 4.0, while retaining the low-end torque producing qualities of the longer stroke. It takes money to make a 258 run as good as an HO 4.0 on the street. Emissions regulations really played hell with the 258s ability to breath. Head flow sucks, camshaft sucks, intake sucks, exhaust sucks.....do I need to keep going?