MP spring relocation kit A body box width for caltrac

Could someone with one of these kits please confirm the inside box width to be 3.25 "?I want to use in conjunction with the modified caltracs.BUT If if the width was 3.5" would the reg A body caltracs work?

I ended up building my own boxes so they would be a perfect fit but I think the standard boxes work. You might just need to shim them a little bit or weld some washers on the inside if you don't like the shims.