Chrysler's alignment specs are not very much different from those of other brands, whose suspensions were designed/upgraded in the late 1950s, as they changed from king pins to ball joints.
The "high caster" orientations got public exposure with the 1973 Monte Carlos, at the direction of then-Chevy manager John DeLorean. He patterned it after what Mercedes was doing. High caster for better straight-line performance, which ALSO needed a steering damper on the steering linkage. When I checked the alignment specs on a later MC of that body series, the alignment specs were "normal Chevy", mysteriously. As the steering damper was also gone, too.
Which tends to follow a GM practice of giving a carline an exclusive feature, gaining popularity and advertising, but after three model years, it's got the normal stuff anyway. Another example was the "Precision" steering on the Olds Intrigues compared to Pontiac Grand Prixs (which shared the platform and plant with the Olds products).
Not to rain on anybody's parade, but to me, ALL suspension alignment specs can boil down to a few things. Get the caster to what the suspension design will tolerate (up to +2 degrees, many times), camber at zero, and (especially with radial tires) toe-in at the min spec (GM even went down to fractions of degrees in the 1980s so the then-new all-season tires segmented-tread tires would wear evenly). Caster can be used to "lead" the car to the top of the crown on a crowned roadway, rather than having to "steer" it there . . . which gets to the "cross-car" spec.
The tedious part of front end alignment comes when you have to get the caster and camber "in spec" at the same time. Finding the "best mix" of what is important. Camber and toe-in for best tire wear, with caster being a bit secondary to those other things.
No doubt, the newer-design Borgeson steering gear (which I believe is made from an OEM Jeep applications!) is "tighter" than the old Chrysler gearbox. I suspect that Firm Feel and similar might have learned some tricks to give the old Chrysler box some "new tricks".
End result, to me, better on-road steering performance is more about having a "tight" steering linkage system, good lower ball joints, tight-but-free bushings, and a steering gear that has the "input bushing/bearing" adjustment to min spec, than how much caster is in the front end. When ALL of these things are changed at once, hard to pin down where the real improvements were made, OR they all contributed a little bit to get the final improvements.
Caster affects steering effort to turn the vehicle and how well it re-centers after a turn, more than anything else. If the steering wants to stay centered, that can be perceived to be good.
To me, the Chrysler geometry is better than anybody elses' back then. I know the "bump steer" people will not agree with that. Especially how "rear steer" is better than "front steer" for having more accurate Ackerman angles. BTAIM
Enjoy!
CBODY67
