Are suspension parts differernt for a V-8 K frame and the slant 6 K frame?

A genuine Chrysler-Plym or Dodge shop manual is very helpful, experienced or new to the game. Also very helpful are the old Master Tech service pamphlets archived at Imperial Club dot org.

Use suggestions in post #5 to track down the problem if it is looseness in some joint. Start with the steering. Jack only one wheel up and move it in and out at top and bottom (wheel bearings) and then left and right. You may need a helper so you can see where the slop is if any underneath (tie rod ends, steering arm or box, idler). Then go check the suspension joints. Use wheel chocks and jackstands if you go underneath the car.

Morris Quay is one of the other mfcs that used to be considered quality. Search around and see if it seems to be true still.
Lemme say I bought my first kit from a Kanter spinoff and it came with low quality tire rod ends that were grease came out all around the crimp. Needless to say I went to the local parts store and bought some good name brand ones before even using the kit ones. If you buy a kit, it might be worth asking for this sort of info.