The older style of chassis plates were still 2.5mm. They have smaller cell slot, and diff cut outs. They also have a slightly different material of carbon fiber as well.
The TC chassis plate is a little softer up front, but stiffer through the middle and rear of the chassis. The older style chassis plates are stiffer up front, but a little softer in the middle and rear.
Lately I've been running an older style chassis (fits my weight plate better
), but they require a different top deck setup. I run the TC topdeck cut where the belt tensioner is, or the older style upper deck. With the TC chassis, I run the TC top deck uncut. Each of those combos are similar in feel. I usually always run an FRP mid plate that is uncut. I find the car works in a wider range of conditions this way.
-Korey