i have a 70 charger that came with a 318 but switching to a 440. had to cut the drive shaft due to rust and could not get it out the conventional way. i was wondering if someone had a 68 or a 69 charger that came with a 440 motor, could i swap it? would it be the same length?

I'm surprised that no one has answered this yet.

You're going to need a driveshaft that was behind a 727 trans (or a 4 spd) and matches the rearend.
I'm guessing that you have an 8-3/4 rear end.

One from a 68 or 69 Charger will be the same, a 68/69 Coronet should be too.

The u-joint yoke that's on the rear end will either be for a 7260 u-joint (2-1/8 inside where the u-joint goes) or a 7290 (2-5/8 inside) which is stronger. But either will work.

I've got a parts book that shows the length but it's in my truck. I'll check it tomorrow and post the length and part number it shows. Odds are you won't find any number on the shaft so you'll have to go by length and u-joint size.

If the 318 had a 904 then yes you will need a shaft with a 727/4sp front yoke. With your selection with the right front yoke butted all the way into the trans I would check that you have 3/4-7/8" end play with the rear suspension loaded & the car reasonably level as tolerances can be all over the place. You might check & see what it would cost out there to have a longer shaft cut down & balanced if you go that route & if so you'd butt the shaft all the way forward/measure from the center of front yoke ujoint hole back to the forward flat edge of pinion flange (where the straps bolt to)/subtract 3/4-7/8"/give that dimention to the shop. when you get it back move the front yoke back & forth in both planes & if it ain't smooth holler back