Nice! I have a 1991 Dakota with the 318 and was familiar with similarities but never noticed that the water pump still used the 4 bolt mount. Just need the pulley to go with it.
For what it's worth, Ehrenburg used a thread-on mechanical fan on project Savvy Savoy so they must work as well.
Been reading back tech articles about some of this stuff and randomly saw that after I posted the issue. Ironically, in the same build, Ehrenburg checked to make sure the fuel pump eccentric fit under the Magnum TC cover, which is where I read that they do so many years ago.
