One problem related to manual transmission has been reported for the 1996 Oldsmobile 88. The most recently reported issues are listed below.
Sometimes during warm-up(not moving). . There will be a loud "thud" at rear of vehicle. At other times I may drive 2-3 blocks before I hear the thud. After the initial thud soud(which is very loud), it will not make the sound again during driving. I suspect it may be mechanical or a backfire. To date the dealership has not found the problem.