Rear Axle Shaft size?

[Guitarplayer]

Purchased an old invador wheel with a what appears to be a sportster rear drum assembly for my Honda chopper project.  I bought a 1979 Sportster 3/4" axle, but it was too large.  Any idea on what year axle or model to look for?  The bearing in the drum appears to be for a 5/8" axle.  thanks.

[Lew]

Probably anybody's guess as to what those bearings were for.  Would it possible to change them out for use with the 3/4" axel.  I personally wouldn't want anything smaller unless there was no way around it.

Lew