It's a hexadecimal system. Hexadecimal includes characters 0-9 and A-F. You can find converters online or create one in Excel.
M (early), 2M, or 2M0 (late) = Mountain Klein
The last three digits are the hexadecimal production number. 642 in hexadecimal = 1602 in decimal (normal) numbering
That's all accurate...and I may have been that guy. ;) Your frame is #1602. As far as components, it's tough to say what is "correct." Klein had catalog builds but you could custom order anything you wanted including custom paint. You could also buy as a frame set only, which could have been...
If it is 03F it would be #63. Not to doubt the OP, but some of the serial numbers are very hard to read so I like to ask for a picture of the SN just to be sure. If it is #63, it's probably an '85, maybe an early '86. Production of the Mountain Klein didn't start till May or later (per a...
You wrote: "Serial number is K MO3F (with the K being the circular Klein logo mark)" Could you post or send a pic of this? I building a database of the remaining Mountain Kleins...trying to photo document them as well.
Not quite complete, but very close. This is Mountain Klein #120
“Before” pic
The “Very Fast Red” / Yellow paint scheme is factory original to the bike. There are a handful of Mountain Klein‘s painted like this. Here is a pic from a period article.
I'm really late to the party on this one but can confirm that early Mountain Kleins had a 27.4 mm seat post and later ones a 27.2. The change was made somewhere around frame #600 - #800.