1985 300CD-T: Exhaust leak

[dogguy]

My vehicle: 1985 300CD-T

Issue:
I suspect that the vehicle has an exhaust leak.
Why?
In recent months, when I have gotten out of the vehicle either when idling or having just shutoff the engine, I smell a strong exhaust odor (no visible smoke though). I've had the vehicle for around 19 years and it is my second W123.153-617.952 and this is a new situation that I've never encountered with either car.

History:
4.5 years and 16,000 miles ago, I replaced the center and rear mufflers as the originals had developed holes due to rust.

Diagnosis work thus far:
I have ever so meticulously (and repeatedly) examined the entire exhaust system from the manifold to the tailpipe looking for holes, cracks, loose assemblies, etc. and found no obvious points of failure.

My suspicion:
A small but smellable amount of exhaust gases are escaping at the joint where the two muffler assemblies connect (attached picture). During my latest inspection, I *was* able to use my hand at the joint to create and observe a small amount of movement between the two pipes.

My question:
What is the typical best practice when connecting the two exhaust pipes? Stated another way: Is there an exhaust-specific sealant/adhesive that is applied before connecting the two pipes and then tightening the clamp? Disassembling the old joint when I replaced both assemblies, there did not seem to be any sealant/adhesive residue though after 30 years that wouldn't be a surprise.

Of course, I could just tighten the clamp more but I'd like to get some feedback before resorting to applying additional torque. The clamp itself is not loose.

I'd appreciate any advice on this. Thanks-