My 250 SL whines a bit at lower speeds in 2 and 3 gear from start to about 2500 rom but the the sound goes away as rpm’s build until it shifts. I don’t hear much sound in gear 4. The whine eliminates as I lift off the throttle (no driveline pressure +\- ) but increases if I lift off completely. Its not a loud sound but noticeable. I don’t think the sound is coming from the rear end. I have read threads which may suggest this is not abnormal as well. I obses about it and all other things that I think might be wrong. What do you think?