According to epc 5970 is the MB sealant. unconfirmed but I've read some MB dealerships use 5900 in place of this, I guess this was not the case for you?

Still waiting to here back about the caulking gun, when I purchased 5970 from MB last time I used a large washer to mount the 50ml cartidge into a regular 300ml gun, it worked ok but the proper tool would be much better.

Hmm weird thing about my ticking noise is it gets quieter as the oil thins up , is only audible above 2500rpm and it gets louder until rpm limit. The grumbling noise <1500 is always there. Clk55 didn't sound anything like this.