I'm restoring a very rusted 69 convertible (Dearborn 11/68). Since most of the underbody needed to be replaced, I used a donor coupe shell for parts instead of reproduction pieces. I ended up using front frame rail through to the rocker panel assemblies as one piece rather than individual pieces. This worked really well as everything lined up beautifully. Since I used the assembly as one unit, the gussets that attach between the frame rail and the torque boxes went with it. Now I need to decide whether I remove the gussets or leave them alone.
My research shows that these gussets were not used on convertibles, though I'm curious as to why they weren't. One theory is that the sequence of events regarding the weld up of a convertible underbody didn't allow for these to be used as easily as the coupe/fastback models. I could easily see them leaving these off if using the gussets would appreciably slow the weld up of a convertible.
Another reason could be that the use of the gussets on a convertible would stiffen the front of the car so as to transfer an excessive twisting motion towards the rear of the car resulting in extra stress/movement between the doors and the C pillars.
I suppose I could just take them off as the "concours correct" thing to do. Any opinions or insights would be welcome.
