Of interest this month (9/2019) at Hagerty.com is their pricing model. You must log in to see all the pretty graphs and such regarding their pricing models, but what I write about is the uptick in pricing for the 1957 Thunderbird, specifically the D, E & F versions between May 2019 and Sept 2019. The uptick is straight up for the most part. Unfortunately, the '55 and '56 Thunderbirds remain flatlined during this same period.
Car prices are an ever evolving phenomenon; however, this uptick is certainly interesting and could be nothing more than a hiccup in the data, but something to keep an eye on.
Hope this helps someone else down the road.