Just do us all (and yourself) a huge favor; make the body with the exact mounting points that come with the frame you intend for the modeler to use. My most maddening project was a resin body kit that was supposed to drop right onto the mounting points for an Athearn 4-axle unit. LIES! You pretty much had to re-machine the entire frame to get that to work. That truly annoying pint was when I asked about that, the vendor never admitted they did wrong in advertising it as such (though they never disagreed with all the work you have to really do). I told them that if you have to do all that work, fine;
just admit that to the buyer ahead of time. they never understood my point. I sold the half-finished project to someone else in disgust.
That company no longer makes kits, I recently found out. Good riddance.
-Lee
Flickr photo set of my On30 layout