i'll bet i've done, and advised/supervised around 100 or so FMJ spindle conversions to date, and have encountered absolutely NO problems what so ever, including bump issues and "ball joint overextension". i respect e-boogers wisdom and knowledge, and really appreciate him writing up these articles [right now, he is doing a two part rear disc conversion in mopar action, using late model jeep components.] but his concern about the FMJ knuckle, in my opinion, is without merit. as to the fatman lowered knuckle, that is, from the pics i've seen, a pressed in pin to a flat piece of steel, welded to an upper balljoint tapered bung. i have never held one in person, nor do i know what material the plate, spindle pin, or balljoint bung, are made from.
The Fatman units are a bit scary looking, but they were designed for the street rod, fairgrounds cruising crowd. I did speak to someone once who had these and I asked him to weigh them. IIRC, they are something like 1.5-2# heavier than the A body spindle.
