You've been such a resource of info and so helpful, thought I'd pick your brain again. In part with my project (near complete now), I noticed a great deal of collected oil/dirt around my rear differential (car now as 142k miles) although I've had no signs of problem from the rear end. Q? - I plan to clean the area well and am wondering what I should contemplate - diff. gear oil change, vent filter cleaning, etc. - any suggestions, pre-cautions or pro-active maintenance other than mentioned I should consider?