You have an LE don't you?
The LE's changed from the 89s to flasher volt 44 style lights (maybe they started this in a last runs as well, I don't know). Stern uses a strange light for this that I've never seen used before. I ordered a special one from Japan for this, that is a 9 LED stacker, runs on 12v, and fits a 44 base. I'll try to find the ebay link, but I haven't received it to date, so I hope they haven't stiffed me.