Get a 5 bar. They can be found on most older 240 turbo's. Sending unit under oil filter, get the pipe that it is attached to. BTW you can use both light and gauge together if you have the sender with both hookups.
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Max..1989 244 DL 5 Spd., V15 Phase II Cam Bilstein HD, Turbo Swaybars, Poly Bushings all round, Turbo Wheels, Black leather interior, Electric mirrors, LED dash and gauge lights and now NEW ECODES with the turn signals, 1992 black 244 next project

As the other gentleman posted, egauges will help with the sender. But, IMHO hold out for the 5 bar gauge, much more usefull than the three. If your engine is in good/normal shape, you will spend most of the time driving with the three bar gauge pegged,since most b230's run around 4 bar, or a little less, hot with 10w30 at speed.

Try Egauges.com. If they don't have the one you are looking for listed, call the tech line number and they will help you out. They were very helpful when I ordered my five bar sender. Good luck and post back your results.