300td bump in rear/leaky sunroof

[bill murrow]

This is my first mbz so excuse me if i ask dumb questions--My 82 300td wagon has a bump in the rear when shifting under light load into 4th and then again on the way back down when it drops to first. Under heavy load when it shifts to 4th the bump is hardly noticeable. Slop in the pinion gear is my best guess but if so how can it be fixed?

Part two is my leaky sunroof,due to rust, I believe, in the front part of the drain. It leaks in on either corner of the headliner. It looks difficult at best to reach to try to plug the rust holes. Is there any kind of sealer I can pour in to block the rust holes? I hope this can be repaired as the rest of the body is in really good shape.

Thanks--Bill