I recently saw a post asking what different characters in a part number mean. Do they refer to a year, body style or what?
So here is what I found out about at least some
Honda part numbers.
I'll be using some old part numbers for this since it's what I have laid out as an example from Honda.
Make-up of Part Numbers
All part numbers are classified into two groups consisting of "GENERAL PARTS" and "STANDARD PARTS". All parts are numbered in accordance with the system described below.
IMAGES ARE NOW AT BOTTOM OF POST/SAVED ON H-T.
New wrenches in the 5.5mm, 7mm, 12mm, 22mm, 24mm and 27mm sizes will be required for the modified bolts and nuts. All other sizes are currently in used.
This change in Hex affects only the wrench sizes: Interchangeability of bolts and nuts are not affected.
There will be a hemispherical dimple on EITHER THE TOP OR SIDE of the nut in all sizes with changed pitch. This will also apply to nuts that are permanently welded to other parts.
All mechanics and parts department personnel should read and understand this change-over, to avoid confusion and damage to threaded parts.
** Info all from the Honda Z600 Coupe / Honda N600 Sedan Parts Catalog
(c) American Honda Motor Co., Inc. 1986