I'm afraid it's become fairly complicated now, due to Honda's mistreatment of the parts situation. They also just quit making the collars, again, in March this year. This is the 3rd time they have quit them, IIRC.
So...
Here's the whole story, regardless of what the parts fiche 'says': The 750K0-K3, CB500-4, and CB550K to 1974 used the early style collar. These swingarms all have grease fittings on both ends of the big swingarm mounting bolt, which is a fancy, precision-made bolt with drilled grease passages and bearing areas on both ends near the head and threads. This mates with the collar, which has hollowed-out ID and thru-holes for the grease to reach the grease grooves, which are fed in the middle section of the bushings. This 'version' of the collar has 0.8422" OD in the bearing areas. The associated bushings are [supposed to be] 0.8430" to 0.8434" ID, and 1.0445" OD, when made in phenolic. These are not flanged bushings, but straight ones.
Trouble is, when Honda switched to making the replacement bushings of powder steel (in the 1990s sometime), they decided to use the LATER bushing dimensions, below...
The post-1973 bikes had a collar with no grease holes, and a swingarm bolt with no grease zerks. Instead, they installed one grease zerk (inaccessibly) in the center bottom of the swingarm (some of the 550F bikes are on top). The collar OD at the bearing surfaces was divided in 2 sections with a shallow groove between them: the inside bearing is 0.8440" to 0.8444" OD, and the outer half is 0.8442" to 0.8448", depending on how the technicians felt that day, I guess? The general idea here apparently was: if you apply enough pressure in the North-American-style grease zerk (about 150 PSI would do it) then the grease could force its way to at least the center groove. Then, if the grease got hot enough, it could hopefully ooze out into the phenolic (flanged) bushings, where the permeability of the phenolic would help 'pump' it along when hot, so it would become thicker after it cooled when the bike was parked awhile. The phenolic bushings became a 1-piece, no-seals, flanged design, and the cups on the ends between the collar and the frame received a dust seal instead. This phenolic bushing ID is made with a -0.0008" to -0.0012" INTERFERENCE FIT with the collar OD, for reasons never explained. The swingarm bolt was changed to be a straight, zinc-plated bolt that fits pretty loosely inside the collars: the original ones had .0020" clearance, while these 'new' ones have up to .005" looseness. Apparently, Honda didn't think this made any difference in the way the swingarm eventually cocks over toward the chain side, with riding?
In 2002, Honda quit making the post-1974 style collars, offering only the earlier ones. This adds .002" extra clearance (on average) to the spec'd .001" manufacturing tolerance. Now, in Honda's own manuals, they recommend replacing the bushings and/or collar when the clearance becomes .0032", because this number DOUBLES across 2 ends of the collar. If you then multiply this by 18" (the average distance collar-to-rear-axle), you get the side-to-side looseness at the rear wheel: (.0064" x 18) = 0.1152", or about 2.9mm (Honda's wear limit as measured at the rear wheel is 3.2mm side-to-side movement). But, if you install Honda's own bushings and the early collar, you get (.0060" x 18) = 0.108" or about 2.7mm, with brand-new parts! While meeting the "letter of the spec", it sure does NOTHING for the bike's handling.
The clearance in the finished, assembled, collar-to-bushing interface should be less than .0010" when new: Honda OEM spec was .0008" to .0012". I try to set them up on the tight[er] side, as they will wear in a little bit right at first.
Right now, I am having a machine shop make collars for me, for the 350F/400F, CB450, CB500/550, and CB750 (and first year of the CB650-4). Not cheap, but they are turning out pretty well, and fairly close to Honda's price. But, they will not work with the Honda steel bushings, nor should they (or any other collar), as even Machinery's Handbook tells anyone who wishes to be a mechanic that "similar metals must never be used as a bearing, or galling will result" (i.e., bearings must always be 2 different types of metals, like steel and bronze, or steel and phenolic). In other words, Honda has seriously made a mistake with these bushings (not IMO only, but all of industry practice agrees), and the reason for this is not clear. When a new Honda collar is installed with these bushings, it takes less than 5000 miles for them to become seriously scored, worn, and even burned, despite the best of maintenance. I estimate that 80% of the arms I get for rebuild now all have had this combination installed, and they are in terrible shape by the time I see them. Sometimes they even rust themselves together, making a solid mass that will not pivot: this then cracks the end caps and sometimes even damages the frame bolsters where the collar is trying to pivot against the frame. (And it is REAL hard to get apart!)
Strange situation?
