Part numbers translation

[Swedemoto]

I thought I saw somewhere an article discussing the background of part numbers prefixes. Can't seem to find it.
Specifically, rear fender for the LM3 is 28460750, the CX100 is 14460754. Last digit is color.
What is the difference between 28.. and 14..? Are they interchangeable?

[guzzisteve]

The beginning numbers I believe have to do with when part came into production or on model year produced that used that part. I'm not an expert on this just been reading current P/N's since mid 70's. Some changed when motor went from round cyl to square. It's pretty confusing cause some are superseded w/a different first 2 numbers only and it's same or improved part. The seals & orings have their own 9070 prefix and secret size code in the number, OR so I have been told. 28 stuff is usually newer than 14 stuff. I think pans are a bit different on how the seat mounts. CX has same tailite but different tank than LM3. My LM3 has a tail piece on back of seat/ CX is like LM1. I've never tried to swap the stuff.

[blackcat]

I wonder if the only difference is the mounting holes in the fender for the turn signals?