1994 Mercury Tracer clicking/grinding while accelerating

My car has a clicking/grinding sound when I'm accelerating which gets especially bad when I'm going up hills. The sound is similar to when a CV joint goes bad, but it does not happen when making sharp turns or U turns. The grinding is most prevalent when accelerating from a dead stop, and the grinding starts slowly and gets faster as the car gets faster. Also, the grinding is MUCH more noticeable after I hit a dip, when the shocks are extended (when the car is in an upward motion, after the initial dip). I had the car checked out by a mechanic who told me that I needed new lower ball joints and struts, which did not fix the problem (they told me the ball joints had some play which turned out to be a total lie - they had no play whatsoever, replaced them anyway - whatever). So at this point I'm thinking its the wheel bearings or the driveshaft (maybe driveshaft bearings?). There is a little bit of play in the transaxle, but I'm not sure if that has anything to do with it. Thanks a bunch for your help!