Hi all. I have a 1991 240 sedan with B230F powerplant and 5 speed manual trans. I have fixed many things on it already as it's 23 years old and has over 150,000 miles on it. One thing I notice some times is a lag in the rear differential or something. When I am starting from a stop, I feel the clutch engage but then it takes half a second for it to get to the rear wheels and there is a slight lurch and clunk when it fully engages and starts to go forward. It doesn't happen every time. Any similar experiences or thoughts? I may need this car to be very reliable in the near future and I need to figure out what or if I need to fix it. Thanks.