1Army E819 Conversion Kit - Adaptive Sadddle Pack Chassis for the HB Racing E819 Vehicles. While we love the handling characteristics of the E819RS, we have always missed the handling characteristics of the 1Army D819 Adaptive Chassis which allows you to quickly adjust between 3 length chassis. So we came up with this option of a balanced saddle pack layout. The standard RS length, the +1 (we call the "sweet spot") or the longer +2 chassis. Machined out of 7075 aluminum, this chassis will take a beating. Each chassis will include all the necessary machined pills to swap between the different length chassis.