The previous writer was correct in stating that 87 and newer 240s have the hole for the lights punched in the fender under the volvo logo. These types of emblems are the ones with the black backing and are shaped like a rectangle. If you buy the volvo original side marker lights from a supplier like IPD you'll get the original equipment that will snap right into the existing hole. The previous writer was also correct that the wiring it up to you. The wiring is simple with a little patience and splicing material.
Here's what you saw:
If you were in Portland OR and it was a black '80 240 wagon and the marker light lenses were orange, you saw my brother-in-law's car. They were added via his handiwork. On the older 240s there is a volvo emblem on the fender, but no hole underneath. My brother-in-law (and since then me, on my 240 as well) simply used a dremmel to cut out the outline for the lights under the emblem. Now, if you were to buy the original volvo side marker lights, you'd pay about 60 bucks for the lights and 40 for the wiring harness. If you go to a junkyard you can easily get a set from an old Saab for about 2 bucks. The wiring is simple enough and you only need about 5 dollars worth of parts. The great thing now is a) you saved about yourself about 100 dollars vs. buying everything from IPD and b) you now have a custom look with the orange lenses vs. the clear volvo OEM product.