These unit can use a drop in decoder. The model are: TCS - AZL4, Digitrax DZ123Z0. Check out: www.zscalemonster.com/azl/e8_e9-truck.pdf The DCC instructions are a sidebar on the second page. The DZ123Z0 is known to have solder domes on the chassis contact points. While in instructions suggest filing them down, I'd advise you to use a bit of solder wick to remove the excess solder.
Greg: turn off the BEMF (CV61 I believe). Definitely does *not* work in Z (they said it is the HO parameters for can motors and won't properly sense the very low Z currents). The 4 functions are great for the SD70 ACe for ditch lights but for the E & F's, the Digitrax DZ123z0 is fine. You'll have to remap the F0Rear to Off (so it doesn't shine thru the shell in Reverse) or use it for dual front light. Like John says, solder wick or suck the solder off the board contacts. Test fit in the chassis (hold the board outside the frame, test one notch at a time. DONT bend the chassis notches, even if not the know issue GP38's. Play with the solder amount first. If still just a bit tight, try duck-bill (flat smooth jaws) to reduce the thickness another few thou.
In either case, the TCS and Digitrax LED's aren't close to the light pipes (neither are the DC Light boards) so the visibility is very low. I cut off the light pipes behind the lense, glued the lenses in with Canopy glue, ran new LEDs from Richmond Controls or Evans Designs. Sucks tho attaching the LED wires to the PC bd after detaching the one on it.