Hi ML11,
The 964 thing is easy.
9 - is the series of car, 240 was a 2 series, 740 was a 7 series, 960 was a 9 series. This is the body of the car, like a BMW model series.
6 - the cylinders in the engine, 240 had 4 cylinders, 260 had 6, 740 had 4, 960 had 6 and so on.
4 - the number of doors. A 242 is a 2 door (the little silver coupes), a 764 is a 4 door sedan and a 965 is a 5 door wagon.
There was a change in about 1985 or 1986 or so that dropped the last number (the number of doors) and just used a zero. A 244 became a 240, a 245 became a 240, not sure if the 740 every had a boot badge saying 744, and a 960 did not exist yet.
These numbers were used for about 20 or 30 years across all Volvo's and save for a couple of quirks (like the 780… ) they were a standard. You will also find the VIN of all of these vehicles is YV1 (The Volvo Cars code) then 964, then some more numbers. Those 4th through 6th characters call out the model on all Volvo cars. Cannot speak for new ones, I am only involved in the old ones, I have a '98 960/S90 and that is my newest car.
Then S90 and V90 and so on started with the new naming convention, the 960 became the S90 in about 1997 which confuses many.
Also, I was at Berry Motor Group last week and they had a fresh 960/S90 with a blown head gasket just left with them, it will likely go for parts. It was blue and in great condition if you need any parts. The interior looked great.
As for the parts database, you are now armed with enough info to deal with it. Try starting with "Hi, I have a '97 Volvo 960 or S90 and I need a blah blah blah part, it may be listed as a 964 as I have had that before".
Or just call a local Volvo specialist, that would be your simplest path.
