I just found a beautiful wood dash out of a '92 to put in my '89 classic (which came with the plastic dash) and while it installed nicely, I can't figure out how to secure the air vents. The vents have a small notch on top which fits onto a ledge in the plastic dash, and then they snap in on the bottom. There is no such lip on the wood dash however, so they just fall right out. Is there a difference between the wood dash and the plastic dash vents? My wood dash seemed to come with all the hardware and bracketry to install it, but I can't see any way to affix the air vents.