Rebuilt T3 cartridge + install $360. rebuild your old one: $260. (603 turbo)

he probably also does the ones for the 5 and old style 5 cylinder turbo. I recommend to rebuild yours if possible, since that's better than a 'new' garrett cartridge that's made in china
still ok though, but not exactly new from the factory like mercedes sells them for over $1000...
call Jeff at:
Turbo Auto Nashville
4403 charlotte ave, nashville tn 37209
615 383 6242
mentioning mercedes forum won't hurt any