I guess a bad ground based on the voltages given. I've seen the direction indicators
on older Fords "glow dimly" with a bad ground in the hear lights or tail lights.
@TourGuide Search through this forum as all that needs to be replaced are the
2 fasteners. The part numbers and a member's remarks are also provided,.. Cheers
Once upon a long time ago, we would put in cams, headers and intake/carb systems.
Wide tires and mags were next up on a long list. So, I think your project is A #1!!!
We used universals to jack the rear up if it was sagging. As long as the
spring seats into the isolator, no grinding necessary. Then grind to fit once
more, the isolator if necessary to fit the vehicle's perch.
Take a picture of the spring "pig-tail's location relative to the upper spring perch (on the car)
on both springs too. Sometimes getting them off may cause a little lean.
How about these???
Fairly common parts.
https://www.oreillyauto.com/shop/b/chassis---steering/coil---leaf-springs/coil-spring-isolators-dampeners--universal-/4588413f406e
It appears Ford has fallen back into the '80s again. Designed obsolescence so that it
might make it to the end of the "Payment Book" (I bet the younger group does not know
about Payment Books with "coupons"). This is the reason people started buying Japanese!
I had to turn as much off as I could. I got tired of fighting for
control of the vehicle. Like the OP stated all of a sudden my 22 ST
would do some of the same things. He might have driven into a flock
of bugs.😉