Pre-war Tech identification

I recently acquired three triangle hole Gillette Techs (pictured below) and I need to know if they're all genuine pre-war models or if one or more is a Frankenrazor.

The caps on the two outside razors look identical (the bar in the center is continuous) to my post war Tech (which has oval holes in the base plate rather than triangle holes).
Several weeks ago I had my hands on another triangle hole Tech (that now belongs to a friend) and it had a cap identical to the center one pictured with the center bar being separated into two short bars.
Looking at pictures on Mr Razor's website it appears that both caps were used with pre-war Tech's but nothing to indicate why the difference.

I also couldn't find any pictures (again on Mr Razor's website) of a pre-war Tech with a hollow ball end handle. I know the one pictured below on the right has a hollow handle because it has a small crack near the top and you can pull it apart.

Thanks in advance for any help on confirming the identities of my latest acquisitions.

 

According to this nickle plated heavy techs with triangle holes are 1938-41. The gold plated ball end with triangle holes are 1938-45. Hope that helps a little.

 

The gold one is a mismatch, that handle is from an Old Type.

 

Thanks gents! I very much appreciate your prompt response to my educational needs.

Chris @WhiskerWhacker , that was an informative link, thanks. Surprisingly it had a link to a Mr Razor page that I wasn't able to find through his website.
It was interesting to note the term "heavy". I had noticed when doing my initial research that the weight was 0ften noted for Techs so now I'm wondering if the difference in the caps was for weight.

Tom @HoosierTrooper , thanks for IDing the gold handle. The lighting in my picture doesn't show it but to the naked eye the finish on the base plate and cap of the gold one is so identical to the finish on the handle that it's hard to believe they don't go together but I also knew that the hollow handles were common to older razors.

 

Here's a picture I took a while back to show the the differences between the ball end Tech and the Old Type handles.