Loop frame police gas tank

[DodgeBoy]

As far as I know now for the Ambos/Eldos there were two different types of gas tank caps. The nice looking flip cap with the small handle on top an a screw on "police" cap.
From what I understood there are two types of gas tanks as well. One has a groove on the filler neck where the flip cap ring snaps in and one with a bit higher neck without groove.

I am just curious about the "police" cap. Was there really a police cap or was it just the same cap like from some V7 special etc?
If there was a specific police cap how exactly does it look. I know there are some old and new very similar styles but how would the very original ones look like?

[Antietam Classic Cycle]

The police cap looks like the ones in your photos. An original cap is partly visible in this photo taken of my 4890 mile '75 police Eldo "barn find". https://flic.kr/p/2nT5LrA

[DodgeBoy]

The police cap looks like the ones in your photos. An original cap is partly visible in this photo taken of my 4890 mile '75 police Eldo "barn find". https://flic.kr/p/2nT5LrA

Thanks for the picture 
I know that the plain flat cap with the ribbed edge would be the correct "non civilian" style so far. But there are quite some very identical of those out there removed from different bikes from Harley to Guzzi.
I was wondering jf there is one specific way to identify an all original Guzzi cap. Like from the looks of the underside because that differs a lot from what I see from time to time. What I see from your picture IT seems the edge is somewhat double ribbed ... ? Or was there even ever that one only Guzzi specific cap anyway?

[JBU]

I currently have 2 eldorados in the garage. One with the twist cap, which I have owned since 1990 and another with the lever cap which I have had for about a year and half. 








The tanks are the same.

[Antietam Classic Cycle]

Scroll down to the fuel tank section. https://www.thisoldtractor.com/moto_guzzi_loopframe_model_differences.html

[DodgeBoy]

Allright thanks guys. That would be another slightly different cap styles.
JBU's has a wider collar on top it seems whilst Gregs picture shows a cap seeminlgy without any collar but a completely domed top without any collar.