608 based Z rod stabilizers. Unlike other stabilizers this is both X and Y adjustable in place to allow precise accurate alignment to provide smooth Z travel! It also can be printed support free.
Stabilizers are provided for both Left and Right sides of the printer, and are designed to be able to have a belt run between them.

A 9mm spacer is provided to position a Timing pulley. This is used so the timing pulley can be used to provide clamping force on the rod and hold it in place, driving against the bearing (For the floating side of a dual Z setup).
A TR8 rod clamp is provided that fits under and into the stabilizer, sitting against the bottom of the bearing. This is used so that the Z Rod doesn't "Lift" out of the block. This is advised for a TR8x1 rod, TR8x8 rod likely doesn't need it.

What to print per side:
1x BearingBlock for needed side
1x Centerer for needed side
1x 9mmSpacer (Optional)
1x RodClamper (Optional)

This is part of my Ender 3 single stepper dual Z system. Find all parts here:
https://www.thingiverse.com/thing:4583416 - Dual Z plate
https://www.thingiverse.com/thing:4581014 - Fully adjustable Z rod mounts / stabilizers
https://www.thingiverse.com/thing:4582645 - Belt tensioner
Optional-
https://www.thingiverse.com/thing:4581024 - Anti backlash adapter
https://www.thingiverse.com/thing:4581042 - Lifted adjustable stepper mount

The complete upgrade requires:
1x TR8x8 Leadscrew (or 2x TR8x1 or TR8x2 or TR8x4 leadscrews, depending on preference. I use TR8x1 for the highest resolution)
1x TR8 leadscrew nut or anti backlash nut (2 if changing both rods)
2x 608 bearings
2x Timing belt pulleys (I use 20mm/60 tooth pulleys, any size will work
1x timing belt (From 696mm to ~800mm, I use 752mm)
M3 mounting hardware and T slot nuts.

Note: Z Rod stabilizers really aren't upgrades! They over constrain the Z rod. No Z rod stabilizers should be used unless the threaded rod is perfectly straight and serious care is taken during the adjustment phase. I recommend only using this (or any Z Rod supports) if you actually need to.