My 98 Chevy S-10 LS 4.3 Vortek auto, 2wd started bucking/shaking/knocking @ a stoplight today. 190K it shakes but seems to run/rev OK in neutral. Clanks/knocks violently about every 5-10 seconds in drive or reverse. The TC has been shuddering for weeks @ 1500 rpm 45/55 in drive, a touch of the brake stoped the shudder instantly and before the breakdown it shifted up/down fine and would not shudder when driven in/shifted to 3rd/no overdrive. Any advice appreciated