Magnum with OEM EFI Throttle cable?
I used a factory throttle cable from a 2001 5.9 Durango intake and throttle body in my '68 Barracuda. Make sure you are routing the cable correctly, it is long and loops forward near the A/C pump before going back to the firewall.
I had to modify the factory firewall cable hole from a round shape to a square shape, remove the plastic bits near the throttle pedal end of the cable and then crimped a ferral, used to assemble steel fishing leaders, just before the factor ferral. It fits and works beautifully. I'm running a Lokar kickdown cable with a 727 for now.