My 95 E300D had been sitting for 5 weeks while I replaced the glow plug harness and fuel delivery valve seals and now I take the car out for a drive and I get a nice clunk in the drivetrain when shifting from 2nd to 3thrd. This is an automatic and I was wondering if it could be the drive shaft discs. I noticed in the history of the car that it seemed to be problamatic. Please don't tell me it is the differential (ring and pinon).

Thanks to anyone who has advice.