According to the schematics at Weber looking at the lower cook boxes for 2005 models.
91079 Cookbox for Genesis Silver/Gold C
91424 Cookbox, Genesis Silver/Gold B.
At the very least, I'd think that a lid from a Gold C would fit on a Silver C and vice versa. Same with a Silver a Gold B. Next question would be whether a C model lid would fit on a B even though the lower cook boxes have different part numbers.
Thanks, I didn't catch that the cookboxes were different numbers. With that in mind I don't think my plan will work. I was interested in the cast aluminum end pieces as they are usually rough in older grills. I was thinking of buying new ones to get back to the factory finish but for the Genesis Silver B they are about $100 each. I started looking around and noted that the Gold C's were about $40 dollars each for what looks like, at first, an identical part. That still is a remarkable price difference for parts that are very similar.
I painted the end pieces on my Silver B with High Temp paint but I don't know how long that will hold up. I have to watch myself about not over doing it on this rehab. I once spent about $4000 restoring an, at the time, $2000 BMW R100S. I kept it long enough to get most of that out of it, and it was fun, but I don't want to get caught overdoing it on a grill of all things!