Someone with brains please decipher ...
 

Im trying to determine nfo about my guitar, the serial is 80175512 - this is what it says on the gibson site (its a gibson SG)

In 1977, Gibson introduced the serialization method that is in practice today. This updated system utilizes an impressed eight digit numbering scheme that covers both serializing and dating functions. The pattern is as follows:

YDDDYPPP
YY is the production year
DDD is the day of the year
PPP is the plant designation and/or instrument rank.

Since 1989, acoustic guitars built at our Bozeman, Montana facility are ranked from 001-499. Electric Guitars built at the Gibson USA plant in Nashville are ranked from 500-999. Prior to 1984, the numbers 001-499 show Kalamazoo production, 500-999 show Nashville production. The serial numbers from the Custom, Art, and Historic division vary depending on the line. The historic reissue guitars feature historically accurate serial numbers.

Examples: 70108276 means the instrument was produced on Jan. 10, 1978, in Kalamazoo and was the 276th instrument stamped that day.
this makes sense to me, and tells me my guitar was made Jan, 17, 1985 (ser # 80175512)

82765501 means the instrument was produced on Oct. 3, 1985, in Nashville and was the 1st instrument stamped that day
this makes no sense to me at all - i know they have to turn january into "0" and they have to make one number somehow from the last 3 months of the year, but how in the blue fuck do they get Oct. 3 out of "276" ???

YDDDYPPP
Y = If 1982, first Y is the 3rd digit of the year 1982 which makes it 8.
D = Number of days. As pertaining to 365 days.
D = Number of days. If it's October 25, 2nd D will be 9. October 25 is the 298th day of the year. (I used the 2005 Calendar. Doesn't include DST changes.)
D = Number of days. The last digit of D. If it is January 7, last digit will be 7. January 7 is the 7th day of the year in the Christian Calendar and DDD of January 7 is 007.
Y = 2nd Y is the 4th number of the year. If it's 1989, this Y is 9.
P = Rank digit 1. This will normally be a 0 if your guitar's rank is not higher than 100.
P = Rank digit 2. This will normally be 0 if your guitar's rank is not higher than 10.
P = Rank digit 3. If your guitar's rank is 27, it'll be 027 for PPP.

70108276
7 = 3rd digit of the year. This means your guitar was produced in the 1970's.
0 = First digit of the number of days. 0, which means it's not higher than 100.
1 = 2nd digit of DDD. It is 02D where D is what we're going to find out in the next number.
0 = 3rd D, 010, 10th day of the year. January 10th.
8 = 2nd Y, fourth number of the year. The year ends in 8 so first Y + this Y is 1978.
2 = 1st P.
7 = 2nd P.
6 = 3rd P. Making PPP 276. Rank is 276.

82765501
To answer your question using my above key schema. The blue fuck -> October 3 is the 276th day of the year using their/your calendar.

85 is first Y and 2nd Y which makes it 1985. rank is 501st.

What I don't understand is, only the 3rd and 4th digit of the year is there. Is there a new or old schema for 1800 and 2000 guitars?

I have a Chinese Calendar which make everything more confusing.

You're probably doing something else while deciphering that's why you got confused for a moment. I checked the way you decipher and the only way you will be confused with Oct. 3, 1985 is either:

1. You are watching porn.
2. You are drunk.
3. You've been reading scales too much.
4. Needs sleep.
5. Needs more porn.
6. Scales plus ear tools change the way your brain functions.
7. I can go on and on and this still won't make sense.
8. Coz numbers 1 to 6 are guesses from a current schema basis.

Manansala is so smart. :)

Made a small script to do it for you.. :-)

http://www.integer.dk/gfy/gibson/