If they're not marked, nope. What I did was put all the bulbs in the cluster and then plug it in with only the multiplug on the back connected then turn the lights on. For the lights that are not illuminated you can just turn the socket on the back 180 degrees... or until they light. You don't have to pull the socket and turn the bulb itself around (unless you want to, of course).

If you want to check polarity before you put them in you can just use any 12v (or there-abouts) wall transformer. Just bend the wires down and touch one to the inside and one to the outside of the transformer plug, which is + and - will be marked on the part that plugs into the wall. I did that for one that I was convinced wasn't working but it ended up I just didn't have a good connection in the cluster socket. I think I used the power cord from my router.

__________________
'83 240D