The new Caterpillar 308 CR Mini Excavator, also announced as the "Next Generation Design" or short “Next Gen” Caterpillar Track-Type Hydraulic Excavator is the successor to the "D" Series, but because Caterpillar has changed his machine type numbering and stopped adding the successor letter it just will be released as the "308" Series.
Of the 308 Series Excavators are the Caterpillar 308C CR by Norscot in 2012 and the Caterpillar 308 CR "Next Gen" in 2019 by Diecast Masters Mini Excavators released both in 1:50th scale.