If you want the year and other info, look at the i.d. plate just above the master cylinder. Write down the info then go to www.volvoworld.com or similar and look it up. This will tell you if it's the correct engine in the car etc..
p.s. don't sweat the electrics, it takes like 5 wires to run this car (I looked at a striped 740 the other day, I could no believe the number of wires snaking all over the place, like a spaceship or something) . On the 120 all the components are very standard, and replacement switches are available used.