[Exim] Routers and prefix?

(Exim 4.20)
I need/want to design a pair of routers that delivers mail to different
smtp-servers depending on local part prefix.

Is there any way to have a router _not_ strip the local part, since I
would like to just do a route, and then use the standard SMTP-transport
to deliver the mail?

Basically I want all mail with the prefix ksd- to be deleivered to one
smtp-server, and everything else to another server.