Small question about disc brake swaps
Yes/no
1972 and earlier you can get sbp A body disk brakes (4 piston calipers) that would go with the small ball joint upper control arm. 1973 and later A body uses the large ball joint and lbp disks. While you can physically bolt in the B/E body stuff, the knuckles are a slightly different height. I've heard people go both ways saying it's not enough to make a difference, and other people claiming you'll never be able to properly align your front end. Do your own research to see what's best or just be safe and stick to the A body 73 and later parts.
Option 2 would be to go to Dr Diff and just skip all the confusion and buy it all in one place.
Anyone that says you won't be able to align the car with the taller spindles has absolutely no idea what they're talking about. And yes, that includes Ehrenberg. He never checked to see if his claims were accurate, and while there are minor changes to the geometry they are not the sky is falling type stuff he warned about. Ball joint overhanging? Nope. Massive bump steer? Nope. At one point he said the FMJ swap was dangerous. No sir, not even close.
The taller spindle increases camber gain, but also
slightly increases bump steer. For the average cruiser, neither will be detectable when driving the car on the street.
If you read the article you linked, the argument is made that on a lowered car with wider front tires (pro-touring style stuff) the difference in camber gain will be a larger improvement than the toe change (bump steer) will be a negative, because the wider front tires are not as effected by bump steer. This is precisely the reason why I run FMJ spindles on my Duster and my Challenger, they are lowered substantially and run 275's up front. I have never had an issue aligning either car, and have not had any issues with bump steer using the FMJ spindles. I did have a noticeable change in bump steer while using 2" drop spindles on my Challenger, so, it's not just because I don't know what bump steer feels like or don't drive my cars hard enough for it to come into play.
Even with the wide front tires and lowered stance, the change between a standard 73+ A body spindle and FMJ spindle isn't something you notice during street driving. It's a minor difference not worth thinking about unless you're driving the car competitively. I did swap my Duster from 73+ A-body to FMJ spindles, again, it's not a "seat of your pants" noticeable difference. If you have 73+ A-body spindles I'd keep them, and if you have FMJ spindles I'd keep those. The difference isn't worth seeking out a swap IMO unless you've gotten to the point that you're blueprinting your front suspension geometry and one or the other does what you need for your specific car.
73~76 A is the same as 70~74 E
the 73+ B and the 80's F/M/J/R is about 3/8" taller and will work fine, and works even better in an application with a lowered car. it's also a lighter casting by about 3lb
you can mount any disc brake kit that is designed for the big ball joint upper, so the years/bodies listed above.
i've installed and sold tons of the FMJR spindles and even run them on my cars and never had a problem with alignment, steering/ride or bumpsteer.
Exactly.
Biggest bang for you buck is the 11.75" B/R body disks paired with the later, 2.75" bore Mopar calipers. They fit under 15" wheels and provide plenty of stopping power, more than some of the fancy aftermarket kits that cost substantially more.