Charlie McNally, at:

McNally Auto Service Ltd
130 Le Page Court, North York, ON M3J3J1
(416) 398-6799

Basically Finch & Keele. This guy is fantastic. Honest, capable and very fair pricing. He specializes in MB, so I'm certain he can handle your diesel. I found out about him on this site, actually. There is a forum for recommending local mechanics.

Jonathan