I run DPU's on my grain and stacker. I have the same 3 engines though. I use 3 Kato AC4400's in 128 speed step with the rear unit running 1 speed step faster than the 2 on the head end, with the rear unit always faces foward with the rear head light on. It seams to keep the slack bunched but I have it set up for NTrak, so you might need to play with yours. I just find that the same model of engine plays well.