8.8 swap

Driveshaft depends on what rear you had before. I had the same driveshaft in my duster with 8 1/4, 8 3/4, and 8.8.
For the 8.8 I had the stock mopar end cut off and the for end welded to my driveshaft and balanced. The length stayed the same. So you should just be able to use a conversion joint.
At the time I didn't know they had one for that, and the junkyard sawzalled the exploder driveshaft, so I had the end of it.
I think the exploder uses 1330 joint. Bigger than stock mopar joints.