170SD, never heard of such a designation, so I had to look it up and sure enough 136.181 or 136.182 w/sunroof, or 136.183 ambulance, or 136.188 police car. Motor OM 636.931.
Opps, that was a 170S-D there also is a 170SD that is chassis 191.110 that has other versions including a station wagon. I bet that would be pretty valuable.
I really have no idea on their value, sorry.
Bosch Master, ASE Master, L1
33 years MB technician