That's worth considering.
The OEM spacer spec is 16mm OD X 10mm ID and they measure pretty close to that.
Measured by digital caliper:
The original sleeves measure at 16MM in the middle, but there is considerable wear where the bushing makes contact with the sleeve; up to .25 mm loss.
The new bushings ID is 16.22mm or .6385. 5/8 = .625 so a nice fit.
The bolts are 9.8mm or .3858 inches. 3/8 ID is .375 inches so 3/8 ID will be a bit to small.
Perhaps replacing the bolts with 3/8 equivalent would fix that issue.
The problem is that I can't find round sleeve/spacer stock anywhere around here, English or Metric, so I'm left with having to order from the internet.
I like the idea of the tighter fit of 5/8 OD, but with nothing in front of me to prove the concept ....
I'm thinking about buying 6 to 8 long sleeves/spacers from Mortch ( 9" long, $4.13 each), and cut to length as needed. Shipping will be steep $40 but still cheaper and faster delivery than ordering from inside the states.
But I'd really like to find a harder steel bushing from OEM. Decisions, decisions ....
In the meantime, I have to put it back together with the worn sleeves :-(