Nope. The thread length of the ZFR5N is identical to that of a Champion N14Y (original plug on pre-'75 Slant-6s and on approximately seventy-three million LA V8s). The electrodes are longer, which is the point of using these plugs—they move the spark away from metal-wall quenchout zones, for more consistent ignition of even marginal mixtures. Of course, they aren't a universal drop-in for any/every engine, because yeah, you do have to make sure the pistons won't smack the electrodes. There's adequate clearance on stock and near-stock 225s and 318s and 2.2/2.5 nonturbos and a fair good whack of other Mopar motors.
There aren't any spark plugs listed for /6 Jeeps because there aren't any /6 Jeeps, number one. Number two, constraining yourself to what you think you see in the listings sometimes mean you aren't going to get where you want to be.