I had a 35 Dodge, on mine the center piece really wasn't needed for support, if anything it was adding something for the bottom of the grill surround to attach to. The grill surround, if in good condition, is self supporting. The center piece probably added support for the vertical bars for each 1/2 grill. All the early Mopar grills I've seen were basically folded sheet metal attached at the top and bottom, with a couple cross braces between the top and bottom pieces, nothing very robust at all. I suspect by 37 Mopar decided they wanted to give those individual vertical folded sheet metal bars additional center support.

If your goal is to make a custom grill, I wouldn't let the center piece be a distraction, as long as your grill design can withstand the air movement at speed and won't fold up in the middle. Gene