Firstfives.org

The wiring harness plug-in to the distributor from the '78 635 Euro leaves a hole in the side of the distributor ( 0 237 302 001 PGFUD 6 ) when removed.

Other ('79, '81 528i, '81 633) all have the same wiring harness's, use plug-in
with a black plastic insert in the distributor, clip as on the injectors.

0237 304 006 PGFU6, 0237 304 015 PGFU6 (spares numbers.)

I've swapped around those with the same plug-ins with no problems I noticed. The old '78 harness, distributor are just extra parts now.

Realoem has totally different numbers for all. Is there a chance the black plastic insert is just a retrofit part ? Remove clip, pull out the insert to make the '78 distributor all same ?

For interested viewers, there's no difference. It appears early versions used a plug on the wiring harness, that morphed into a plastic insert in the distributor,...that the later harness connectors plugged in to.

Seeing the insert on all exploded view parts drawings gave me the courage to pull one out of a distributor, to see it's the same as one without the plug.

I got away with it. Two good ones now, not two junkers.