My 1995 Subaru Legacy L AWD w/ 5spd manual transmission is making a rumbling noise when idling and while drive with the transmission engaged. This started a few weeks ago and has gradually gotten louder, and now squeaks while driving. Also, the speedometer jumps when I slow to a stop, but is steady and seems accurate while driving.
The clutch was replaced November 2008 with about 190k and presently has 209k. The mechanic that replaced the clutch and looked at it yesterday and said that there is a main bearing in the transmission that has worn out and is causing the noise. He stated that the clutch is fine and did not mention the throw-out bearing when I asked him about it. He also said this is causing the speedometer to jump.
The mechanic replaced the gear oil and added additive as a temporary fix but said the transmission need to be replaced. My question is, does this sound likely or could it be something else?