Extreme clutch shudder

Something has gotta be broken or loose somewhere. This isn't making sense.
completely rebuilt suspension everything is tight, they are original leaf springs I disassembled and rebuilt, all u-bolts are new and tight, new leaf spring shackles and shackle boxes, motor mounts are good, transmission bushing good, care only shudders in 1st gear not in second or reverse, the tech at brewers I've been talking to seems very sure its pinion angle issue.