Have you checked the rear suspension bushings? Worn rear trailing arm bushings on my 245 gave clunks on backing up then starting forward and also on rough roads. I've read that worn torque rod and track rod bushings can give an unstable steering and tracking. I replaced my torque rod bushings along with the rear trailing arm bushings and shocks plus struts. A huge improvement!

I did have a clunk in the front after replacing the struts. It turned out to be the strut cartridge retainer nut needed another 1/3 turn to tighten up. An IPD publication listed several bolts in the front to tighten if there were clunks. As I recall they were the bolts on the front cross member, the rear bushing mounts and the steering unit. Worn front bushings can also cause klunks.