Frame I.D. question

I bought a frame that is supposed to be a 35-40 ford car frame but some of the dimensions are a little off what Wescott has on their site. I sanded the left rail and found this number star 1500835 over the rear wheel arch and above the front body mount, the front numbers are no longer visible due to modifications made by a previous owner. Any ideas?

 

http://www.wnyrg.org/tip.html

 

If a little off is measured in 1/4 of an inch, that is Ford tolerance specs.