Can I use same driveshaft??

There is a hole drilled through the spring stack with a bolt that holds the spring stack together, that also acts as a locator for the axle. To move the axle you will need to add another hole and bolt. Depending on how much you move the axle the old hole may be exposed to the flexing the spring goes through and fracture not to mention the changes in spring action.

For the $75 or so to have a drive shaft cut, balanced an new u-joints installed i wouldn't hack up the spring set.