If there's oil on the clutch making 'er shake, start in first, you may find that helps as you don't slip the clutch as much.
Also, does the 3/4 ton have a carrier bearing? If the driveshaft can jump up and down, it'll shake too. This happens on 1-tons, when the rubber ring that holds the carrier is worn/missing. I've never been under a 3/4 ton before.
