Technical 1942 GMC marker lights

I got my head light buckets off eBay, does anybody have any dimensions on the small marker light lenses that go on the buckets. I'm trying to figure out if I have 41 or 42 up buckets. I know the 42 up lenses are bigger but can't find out how much bigger. Any help would be appreciated

 

The later version has the bulb socket in the h/l body - early type uses '40 Pontiac parking lamp ***'y.