My 87 K5 has started shuddering really bad. Considerably worse when accelerating and decelerating. But still shudders at all speeds. What could cause this? My 87 K5 has an automatic transmission with automatic hubs. It is stock with 111,000 miles on her. Looking thru past receipts the previous owner replaced a rear u-joint at 102,000 miles because of "driveline vibration". I got under the truck and didnt feel any slop in either the front or rear drivelines. So can I rule out a u-joint? Thanks for any and all comments!