I'm not sure I kept everything straight as I read through this, so maybe it's all figured out already.... but...

I cut a '75 K frame apart last week and have the parts in question still laying on the garage floor. I may have to cut the pivot a little more because I ket the section with the rear motor mounting holes together so I could adapt it to my engine stand, then remount the engine... so much for that idea. I'll take pictures if you still need them, then you'll know it's the right stuff.