Joseph Cummings's post in Tito was marked as the answer
When you open them up that big there are a lot of structural considerations. Probably be fine if you are building a trailer queen show truck, But if you put it to work you better have added some structural reinforcements or else that cab is going to crack starting with the upper rear corners of the door frame and getting worse. Have you ever seen an R Model that has been run with the bar between the steering axle's spring hangers that everyone thinks is just to hold up battery cables and the fuel crossover, missing or loose? It'll break the cab up just like that. And believe me, that is a hard fix
Joseph Cummings's post in Tito was marked as the answer