I used a sedan frame under a '40 truck that I owned some years ago.I removed the sedan body mounts from the side of the frame rails and it worked out fine.I'm not 100% certain but I think the body mount brackets on the sedan frame are the only difference.The mounts are riveted to the frame just in front of the rear kick up.Hope this helps.
Yes the truck and car frames are the same from 35 - 40. The only difference is the the car frame has body mount riveted to the frame near the rear section just in front of the rear axle. The frame was changed in mid 36 at the rear cross member that is not big deal.
Car and pickup appear to be the same (except the car body mounts) but the pickup was 10 gauge, car was 11 gauge. Dont let that stop you from using a car frame for a pickup
The shop we purchase our 35-40 rails from has pu specific rails. I compared them to his car rails and they have the same overall demensions but there are some holes in different spots.
I would have to agree with you on that. I have a pickup frame under my sedan and needs some patch panels for the side rail. I order them from one of the Co. that make them just for the 35 to 40 ford frame and they were suppose to be 11 gauge but the were thinner then the rest of the frame. I called that co. and they said they were right and all frames were 11 gauge. I guess they were wrong.