Drivetrain How to fix driveshaft rubbing on the floor pan?

This combination of springs and dampers has been put on this chassis a lot and he should have zero issues. I ran this combo and had zero issues.

There are mechanical issues with the current control arm bushings that are most likely 100% of the problem. No shimming to change drive line angle, lowering of crossmembers, raising of the car’s ride height etc. should be done until the bushing issue is addressed. Once that is done the driveline angles should be checked and will most likely be good to go but if not address it. OP should then take the car for a spin and see if the issue with the DS scraping is solved and if the vibration issue is solved. If not them start working the problem methodically one thing at a time.

Until the bushing issues are corrected we are throwing darts blind folded.

Mike knows his stuff and so does the General so pay attention.

Well, I agree, if it has heim joints type suspension pivots, you can tighten them any way you want
It'll be a clanker either way over bumps
The rubber was there for a reason

Jesus man, I have a full MM suspension under my Coupe and its quiet as a church mouse. My T-Bird is a full Griggs car and again quiet. Rubber was there due to the crap angles of the four link and the known binding issues. Does is help with NVH? Sure but most of us are willing to deal with a little NVH to gain some performance.

The MM stuff does give the illusion that it's a heim joint, probably the best of both worlds design (which is why i wouldn't use anything else).

Similar to having solid motor mounts
Try them, for me, once was enough

If your around central Florida, you can use the stock 2 3/4" that came out of my 83... I assume it would fit
I had a new 3" steel tube built for my new rear/TKX swap

@AnthonyA1234 - is that D/S 4"? The SS springs + OEM LCA's will sit the ass end of the car LOW. If you're riding on or contacting the pinion snubber (shorty), you have sheet of paper (or less) clearance going through the top of the tunnel. With a 3.5" D/S, those springs and non-adjustable LCA's (the box alum type - and spring sits higher than OEM LCAs) it would hit the ebrake cable. I changed to the MM adjustable LCA's, lifted the back of the car up 1.25" and didn't have a problem again.

When sitting low, these cars don't have a ton of D/S space at OE driveline angles. Add a larger diam D/S and wore out bushings, you'll end up with more pinion lift and then contact. Changing the trans crossmember for more clearance will only screw up your driveline angles, so you'd be trading 1 problem for another.

It looks like you have a few items you're fighting here, but the drop of those springs + big D/S aren't helping the situation.

Again, I ran these springs with stock control arms and the FMS driveshaft with zero issues. I am lower now with the coil overs and it only rubs the ebrake cables if I am really stressing the suspension.

Fix the bushings and then if needed make moves from there. We know the bushings are back and causing the rest end to move all over the place and in directions it normally would not. One thing at a time.