I got a reply from Quaife our cost is $1970.73 + shipping. here is the answer i received

Hi Jim,

Thanks for your enquiry.

Please find attached offer with payment instructions. We have
these in stock and can ship as soon as payment is received. The
Quaife also comes with a pair of Mercedes output shaft seals.

To be honest, I would be absolutely astounded if Wavetrac (or
anyone else for that matter) had anything that Quaife don't
already have. We've spent the last 8 years commissioning all sorts
of Mercedes Quaife sizes, for old and new models, and carry them
all in stock. Everything you see on our price
list is available and ready to go.

This is yet another reminder why we should be stepping up our
efforts to improve visibility in the U.S, and plan to do so later
this year!

Our Merc
install guide is here if your workshop needs it. It's for a
different model of course, but the principles are the same.

I don't have any further info re the SLK32 in specific, but there
is some info on the Quaife ATB on our
website and of course on Quaife's
website.

Let me know if you have any questions at all.