Technical Dimensions of early vs late pickup boxes

I'm bad at searching I guess, and this is likely a stupid question but I couldn't find whether there was a significant dimensional difference between an early and a late Ford pickup box. Fenders are different obviously but would, say, a 34 box fit a 36 frame? 36 frame is wider presumably, but by enough to really matter, especially with fenders fitted?

 

btt

 

Bump once more

 

I know 35,36 and 37 are the same , the fenders also I think

 

How about early boxes on late frames? 34 box on 36 frame, for instance.

 

Here is a link to a place that makes all the parts of the beds Model A through F1 at least.http://www.mack-products.com/products-page/ford/page/7/ . From the way some of the parts are grouped together, 32-37 may all be the same width.

 

Awesome. Thanks much