I fully understand the issue with the rear upper shock mounts and their design intent, BUT . . . I put Gabriel Hi-Jackers on the rear of my 1970 Monaco Brougham to get the rear raised enough to not scrape the rear factory dual exhaust tips on driveway entrances and such. Just enough to level it out, which usually as about 60psi (minimum pressure of about 30psi, according to the literature which came with them).
This was back in about 1975 and the shocks are still there, having been replaced a once due to age. At the time, the Hi-Jackers were popular with people who wanted to raise the rear suspension to clear overly wide tires on the rear. The had a shield to protect the (allegedly fragile) air bag from debris and such which the tires might kick-up. Compared to the similar Monroes with no shield.
By observation, when I did that, it was the best choice. For time and expense. Sure, there are many spring shops which do heavy-duty trucks and such. But with all of them being 30+ miles away and NO experience with them OR how what they did might work and affect the ride/handling of the car, I got the Gabriels from a local auto supply and they worked fine. Even made the car act like it had a bit of a rear sway bar on it, which was neat!!! This car, when I bought it, had Monroe Load-Leveler rear shocks, which were old and did not do as they advertised. The car had been used for trailer-towing by the original owner.
Back then, too, getting new rear springs from Chrysler was not possible or desired due to cost. Again, even if available, not sure they would do what I wanted and not mess with the ride dynamics OR carry the weight of people in the rear seat. All I wanted was a level car.
On my '80 Newport, it came with some private-brand Monroe air shocks and a home-made trailer hitch. They were bouncy so I got a new set of Monroe Max-Air, as that was what was on it.. And they are still there, with minimal pressure in them.
ALL of the air lines, then as now, are plastic lines. If routed correctly, NO issues.
In one respect, having little constant pressure on the upper shock mount area can be much better than a very stiff rear shock and a very rough road's pounding on those mounts and their related body mount areas. As with the Monroe HD rear pickup shocks, from the mid-1980s and later, when the upper shock mounts got slightly loose and wallered-out the holes in Chevy pickup truck/Suburban frames . . . on smoother roads.
Monroe was Chrysler's vendor for shocks back then. Hopefully the current Monroe operatives have not changed the internal valving since back then. Or decreased the quality of materials and such.
By observation, spring shops do not taper-grind the edges of the leaves they build, just "rough cut" ends. Not having the tapered ends can tend to "ruin things" for me as it is NOT what Chrysler did back then. Which, also, can mean the rest of the spring will not last as it should. But they are a somewhat less-noticeable alternative to the older bolt-on helper leaf springs of old. In modern times, I might still be oriented toward air shocks as I have had good experiences with them, to just level-out a set of sagged rear leaf springs and not ruin the ride, yet improve the cornering a bit without having to add a rear sway bar.
Just MY experiences,
CBODY67
