I think that there are two sending units on the 208 as there are in the 202 chassis. There are two separate areas of the tank and fuel is lifted from one side to the other by a jet-pump siphon arrangement.
Both sending units are in series and read about 200 ohms (making each about 100 ohms if I recall). One side full and the other empty will give 100 ohms plus zero ohms. This would look the same as two half full tanks at 50 ohms a piece.
You will need to find which one is bad and then I would pay someone to replace it as it is a nasty job. It is a job only my trickest tech can accomplish as they have quick connect fittings that don't and they have to be manipulated virtually inside the tanks. If left to my hand skills the only solution would be a complete tank install. I could never get in there to do the quick connects.
Bosch Master, ASE Master, L1
33 years MB technician