Ehrenberg's concern with the FMJ spindles isn't without some valid points. Yes, they bolt in and work without issue for 99% of applications, however they are in fact taller than the recommended '73-'76 A-body/'73-'74 E-body spindles. That does upset the excellent geometry of the Chrysler front end somewhat, which I would only expect to be an issue in extreme hard driving situations such as road racing, autocross, and me on a lonely back road with better curves than Marilyn Monroe. The other concern comes directly from that change in geometry: simply put, you are now imparting stresses on the parts for which they were never designed. Will they actually break? Well, I don't claim to know. I have seen one instance on a hard-driven '72 Scamp where yes, it did snap the upper ball joint--exactly his main point of concern--but short of a metallurgical diagnosis I don't know if it was the disc brake swap or simply a defective ball joint. I also know of several other cars with the FMJ parts that have not had any problem, but at the same time they were/are not driven in the manner of that Scamp, either.
I know others have "proven him wrong" but I've not seen what I consider conclusive from an engineering standpoint. Running the suspension from full compression to full jounce with a floor jack is one thing; mathematical assessments of multiple stresses in several directions on a particular metal alloy is quite another thing entirely. So, I'll do it the "factory engineered" way myself. I've found the limitations of way too many parts over the years, sometimes with rather spectacular results.
I'm 100% with you (and him) on both the Green bearings and the rear disc brakes, though. In fact, I've been preaching the same thing for years about the Green bearings. There's more than one way to skin a cat when it comes to the rear disc conversion, though. Still, for the virtually undetectable difference they make in actual braking and the fact that I don't care what you see through the openings of my rear wheels, I don't consider the time and expense involved in such a conversion worthwhile. People who claim they got vast improvements by switching out their drums for discs universally had neglected, misadjusted, or unlubricated drum setups in the first place. If the drums are adjusted and maintained correctly, you'll not likely see much if any improvement by spending all that money to swap to rotors.
