2 and 3 pronged oil cap

[sujitroy]

I'm going through my stuff of spares here in USA and have found a few 3- pronged oil caps. One is on an engine which came out of a '72 Stag, but the one on my May '71 is two pronged. What's the deal with having 2 or 3 pronged caps on the Stag? Obviously the cam covers have to match as well so would have been an added cost.
Sujit

[KOY 23]

2 prong saves the cost of a prong and a hole.

[jbuckl]

2 prong made the cover collar simpler & cheaper as well.

[stagx790]

Herald/vitesse petrol caps fit the oil filler can’t remember if they were 2 or 3 pronged.

[SaskStag]

3 prong caps are rare. I searched high and low for one to replace the broken one on my car. I even searched for Herald caps.
I eventually got one from a Dutch scrappy.

[flying farmer]

I have a 3 prong on my Mk1. It came without a cap.
Fortunately I had a spare Toledo fuel cap in my shed which did the job, once I had epoxied the vent channel that lets the tank breathe