Drtyfn, thanks.
Things are a little bit more complicated than 3157 or 4157. Stock is Sylvania 4157K, manual says 3157KX/4157K. The 3157 bulbs I found seem too small, and have many different bases, there is no 4157 on the net.

This the reply I received from bulbs.com
Good afternoon, In response to your email: We do carry the 3157 bulbs but I'm not sure what the KX refers to in the model number. I was able to find some information on the 4157... these are pretty much the same bulb. The 4157 is slightly higher in amps and they last a lot longer but the dimensions (according to the catalog I was looking in) were the same along with the type of base. You may want to contact a manufacturer of automotive bulbs. Maybe they can refer you to a place that carries the exact bulbs you need... they can also explain the differences between the two types. If you need anything else please let me know.