As a late B body owner & lover, the rusty area's that need to be looked at closely are;
1: The rear of the K frame where the rubber biscuits are. The ISO suspension system is a good ride BUT where the K frame narrows down to hold the biscuits are, water and road debris tend to collect and rot that part of the K frame out.
If it is so rotted, the K frame can and will collapse. This area is simple to fix but a pain to get to since, well, it is holding the engine in the car. To state simply, remove the attaching screw and drop the K down enough to weld in a patch.
It is not actually hard to do. The metal is not thick, just layered. If you can weld, this is a snap to fix.
2: the rear springs sit sandwiched between two rubber biscuits that sit inside a metal "U" that bolts to the upper portion of the spring holder. This sandwiching of parts to retain the springs to the axle catch a lot of road debris. Under a lot of power or a use after many years, (I have personnaly) they will fail and physically get ripped apart. Aftermarket parts area zero for replacement. But available for the F, M, J guys. The parts do not swap. Rewelding or a swap to an earlier year suspension is the only option.
3: rear bumper area. Look over, up and under the back side. It can get very rusty there.
4: these cars seal well. Which is almost a good thing. Here's the problem. Water gets in, water stays in, water rusts the floor under the carpet AND will also rot out the roof, sail panels, inner doors, etc...
I have had a pair of cars rust to crap from the inside out in a few short years.
Remove the entire interior and remove all the rust you can and then treat the floor with something like POr-15, Rhino liner, Navy battle ship paint, something, anything!
Lastly, look at the cowl area where the water drain flap is, a small oval rubber approx. 2-1/ in length across. This is where the water drains from the cowl. Leafs get caught in there and hold water rotting out the cowl.
Also inside the cowl should be cleaned. The air vent, passenger side only, gets rotted out. It can cause (as in my case) the door hinges on the passenger door and the wall there attached to to rot out. The water will also rust out the metal under the door and the bottom of the door.
After that, the typical areas are all ready probably rusty. Behind the door/rear quarter area, behind the rear tire, the inner and outter quarter. Trunk floor.
So far, there is zero aftermarket support in panel replacement. Your only hope is a good donor car.
Be aware that the rear springs have a larger locating peg/nut for the larger upper spring plate. Also the T bars are longer. Earlier B body T bars do not fit. Though a company like PST has the longer bars. Rear shocks have stud on the bottom.
Watch for rot as pictured. Behind the door at the hinge areas, even more so on the passenger side.
Also where the hood bolts down onto the cowl.
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I don't know if you can see or blow up the picture size to the passenger side where the door hinges go, but there and where the cowl' stop meets the firewall and the top portion of the hinge area is where the fresh air vent is inside the cowl. This area had a good bit of rust.
(Paint is Spiniker White. Taken and posted with the phone again, sorry.)
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Click this ---> My thread titled, "Rear suspension woes" that show what I was talking about.
http://www.forbbodiesonly.com/moparforum/showthread.php?582-Rear-suspension-woes
aboard!
