I don't know if the Crestliner's ignition switch is different than one on a '51 Custom, but on my car, I was always afraid the the tabs on the plastic insert on the ignition switch would wear out. (I had to take it apart a couple of times.) I kept checking on eBay and about 6 months ago, an NOS one showed up for $20, so I grabbed it. I don't know if this is the same problem, but keep your eyes open; stuff shows up at the craziest times.