Does anybody have any experience swapping from a Harley 5 inch speedo to a 3 3/8 inch speedo?

i have a 2011 FXDC with the 5 inch speedo and i bought a new dash, ignition, light cluster and speedo from a 2010 FXDWG because it looks much nicer. when i plug the new speedo into my bike nothing happens. When i plug the new speedo into my friends FXDLS it at least lights up. I’m guessing that means different locations for wiring in the connector but before i start doing that i was hoping someone here has done it.
When i plug the old speedo into my bike it still works.
i reached out to big bear choppers since they sell kits to move the gauges onto the bars can but they were no help at all.

I believe the speedometers are married to the bike and have to be transferred via a cable to work. I know to change mine that has to be done and it’s an older bike than yours.

yep they are. But the fact that when i plugged the speedo into the 2017 FXDLS it at least lit up means something is wrong because when i plug it into mine it will not light up