Short Chainguard
The first 26,845 CB750's delivered in 1969 came w/ the notorious "short" chainguard. Complaints of chain lube slinging on passengers riding-#$%* saw Honda superceding the elegant 24" original w/ a really dorky-looking 26". Rear chainguard bolt on a short chainguard is a unique 6x70mm and cannot be installed w/ #1 pipe in place (which you always forget until its time to do it).
Rolled Rear Rim
A beautiful detail unique to sandcasts and a couple thousand early K0's is the "rolled-shoulder" rear rim. The rim shoulder is distinctly rounded as compared to all the later rims which have a right-angle shoulder.
Dull Heat Shield
Sandcasts and K0 heat shields were not a gaudy bright chrome, they have a rather industrial-looking dull aluminum finish. Very rare part which can be cloned very ez by simply painting a chrome shield w/ aluminum paint (tip of the day).
OEM 45T rear sprocket used on all sandcasts and K0's along w/ a 16T front, which was superceded very early by a 17T and a stronger chain w/ a riveted master link. Apparently the 16T's had a hardening problem with catastrophic chain-breaking causing all sorts of broken sandcast crankcases (I hate when that happens). K1's had 18T/48T
Swingarm unique also with different chainguard mounts from later models.
Note the tightly-wound spring and SHOWA Decarbon sticker on rear shock. Top "eye' (not shown) is black, not silver like later models.