GMC had a parking light that exposed the flat part of the fender for 54 and early 55. Chevy used a completely different grill in 54 and early 55 than it had used in previous years and it covered the flat spot. The 54, early 55 is hard to find if you need one. You can probably trade someone for the one you need. Late 1947 through 1953 is all the same which means there are a lot more of them around. This catalog illustrates the difference.

http://www.tuckersparts.com/RESERVED-c-361/