I was expecting them to do the 74xx and late 64xx as a follow up to the early 64xx. It isn't exactly that bad a job to do for the late 64xx, the only really obvious difference is the cab roof and bunker top corner. The 74xx is a bit more complex and would need more part retooling but the design required to get there isn't great. It took me a couple of evenings to do the main changes to the cab roof/bunker area, ATC box change, lever reverse, tank side handrail and remove auto jumper box. I left the brake hangers but did add some missing conduit, lamp irons and running plate handrails,