7.25" to 8.25" driveshaft?

I'm upgrading from the 7.25" rear in my '73 Duster (904 transmission) to an 8.25."
From my reading on here, it would appear that I need to either shorten the Duster's driveshaft or find a different one. Can I pick one up from the junkyard? I can pull one off an '83 Cordoba or an '85 Diplomat, both with 8.25 rears and both with 904 transmissions. Those are slightly longer cars than the Duster but would one of them work?