Thanks for the heads up but at the HET website (and another that has the same books online), there isn't a shop manual that has the frame dimensions online but only the frame part numbers. Haven't asked yet otherwise.
No, won't be going for the minor makes pre war. If I was to include EVEY car manufacturer then I would both go nuts and broke keeping up the website. There were literally hundreds of auto manufacturers with many going out of business by 1930.
So, I focused on just cars that had X Frame bracing. That includes US cars made basically between 1932-1964. That is a task in itself and not all manufacturers used the X-Frame or not for very long but a majority did during that time span.
If anyone has manuals, bulletins, books that show frames with dimensions from the 1930s and early 1940s, please let me know. Always looking for help with scans for the project. Thanks!