Actually, it doesn't really matter which side "the plug" is on, only that it plugs into the Duraspark unit, which is why it has its own pig-tail instead of the connector being cast into the housing or cap itself. Over the years, Ford changed the castings many times. The link below shows a pic of a 351W small-block Duraspark2 Ford distributor, with the pig-tail on the same side as yours.

Small block Ford distributor for vehicles with Duraspark ignition. Late 70's-early 80's.

References:

http://www.summitracing.com/parts/aaz-30-2831?seid=srese1&gclid=CNPfqNDNxcoCF...

Reason:
Thank you for your opinion, but I can't find a distributor of that brand with the plug on the same side as ours. Could you provide a reference with the plug on the same side and we can accept it?

Actually, it doesn't really matter which side "the plug" is on, only that it plugs into the Duraspark unit, which is why it has its own pig-tail instead of the connector being cast into the housing or cap itself. Over the years, Ford changed the castings many times. The link below shows a pic of a 351W small-block Duraspark2 Ford distributor, with the pig-tail on the same side as yours.

References:

https://www.google.com/imgres?imgurl=http://www.classicinlines.com/images/Tec...