Hi,
A PE/resin set for the GMC Duece and a half is available from Verlinden Productions. Kit # 1314. It includes a Resin. .50 cal MG, M3 ring mount, complete engine, fuel tank, firewall, upper decking, radiator, tools, fuel & ammo cans, stowage, wipers and more and a large PE fret. They also make a Duece and a half engine for the tamiya kit. THe engine kit # is 524.
Hope that helps
Matt