Royboy-
The Gen 1 BMW was 2012 -2015 model years. The 2016 & up 2020 are Gen 2 . Also you can tell by the exhaust pipes if it's Gen 1 or 2. The Gen 2 pipes are kinda swept upwards & have 2 pipes . The Gen 1 has a smaller fatter , more horizontal exhaust pipe
The Gen 2 should have hydraulic timing chain tensioner installed at time of production
Good luck on your search . Remember C650GT was discontinued by BMW after 2020 model year . Only the C400 is still in production. A bit of advice on the C400. Don't buy any of the early models. Year 2021 & up are better made, but more $