Part numbers changed over the years due to programming changes in the computer itself. The OBDI guys weren't flash-updateable... so, if you wanted to change the programming, had to replace the whole thing.
There are parts manuals available for download in the faq section here, might wanna browse thru the correct one for your year, and see what they have to say.
1996 Ram 2500 5.9 EC/SB Gas, Auto, 4x4, Hughes plenum plate, Kegger mod, double roller timing set, rest is stock. For now.....