Continued working on the instrument cluster today. Whipped up a wood buck to shape the housing around, then cut a strip of sheetmetal out of an old bedside from my F150. After a little shaping, it fit the frame perfectly. The little tabs on the frame weld to the housing to lock it together while keeping the welds out of sight. Next, I'll need to cut the overlap out of the housing, weld the seam, weld the last few tabs, then bolt it into the truck to determine the angle for the back panel.
