Unknown M1 Helmet shell

I have a M1 helmet shell of unknown era.. I suspect vietnam or late 70's.. It is a front seam shell with single snap chinstrap and no markings anywhere.. I know little to nothing about the M1, I have only used the PASGT and ACH with my time in the Army. I plan on selling this and it would be very helpful to have some information on this exact item I have.. Also, how much could I get for this?

https://www.milsurps.com/images/impo...c00941pa-1.jpg

https://www.milsurps.com/images/impo...sc00940d-1.jpg

https://www.milsurps.com/images/impo...c00939ms-1.jpg

You're right about the vintage. Late pattern swivel bale from probably 70's or just before the Kevlar. It should have a heat lot number inside the front. Numbers-letters. That would help to identify it. Hard to say in the US, but here in Canada you could probably ask $50 or so for it.

Thanks for the number/letter tip, It is very hard to see but it says "101G" Any idea what that means? I thought they stopped making front seam helmets in the early 40's?

If you search around on the internet for M1 helmet identifying numbers, you'll come across the codes. Some of these people on the other sites like War relics forum discuss that very thing. I think you'll find this is a VERY recent helmet outer.