In Volvo parts catalogs most part numbers have an extention number at the end (for example 682294-4). Sellers of Volvo parts don't seem use these extention numbers. What do these number mean? Why are they there?
Tom

I'd defer to Bram, but this also says "check digit" to me. So I looked at this site's 700/900 FAQS, which are accessible by sending a $30 donation to Jarrod, whose name and address appears on the home page.

The FAQs here

http://www.brickboard.com/FAQ/700-900/PartsSources.htm

say:

Volvo Part Numbers: Secret Check Digit. The secret Volvo formula for a check digit is as follows: 1212121 -the next whole number divided by 10. example 6 6 0 8 2 8
multiply each digit, digit by digit, by: 1 2 1 2 1 2
equals: 6 12 0 16 2 16
Then add the resulting digits as: 6+1+2+0+1+6+2+1+6 =25

and subtract from the next closest number divisable by 10 and the remainder is your check digit (5). Hope this helps - I worked at a Volvo dealer for 18-years and found that the Volvo check digit always kept you from accidentally ordering the wrong part (did not keep Volvo from sending the wrong part). Knowing the formula allowed me to order parts that I read about in non-U.S. bulletins.

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Well, see the FAQs for better formatting.

And I was just kidding. You don't NEED to donate, but it's real cool if you do. :-)

Unless I am doing something wrong, that crazy formula might work for newer models but it doesn't work for vintage Volvos. I tried it on the B20 radiator cap number that is listed in the catalog as 682294-4. Using that formula I first multiplied each digit by the 121212... I came up with 6 - 16 - 2 - 4 - 9 - 8. So then I added together each digit 6+1+6+2+4+9+8 = 36 That would give you a "check digit" number of 6, but it is in reality 4.
Tom

Um, it worked fine. 36/10=3.6 round up to the nearest whole number and you have... "4"

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Mike!

Usually revisions of the part. Not particularly significant, and I don't think Volvo themselves use it much (except perhaps for some high-level stockkeeping?).

Bram