To answer the original question - that of interchangeability - look through the FSM to see the variations of the same theme.

Around 1988 and 1989 (if I remember correctly) the sensors and wiring changed a little bit. So I wouldn't get anything from 1988 onwards it is unlikely to be a plug and play solution.

The addition of a sensor on the back of the speedometer (road speed sensor) was something that happened towards the end of the CIS engines: If your car was newer I'd say that that might be worth checking but I don't think it was fitted to 1986 models. (Still thumb through the FSM and check)

So long story short - if you really want to swap ECUs it is probably best you get the same Bosch part number - this would limit the cocking about

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!