I would call the place you got the driveshaft from and tell them it doesn't fit and give them a measurement that will work. Remember to make an allowance for the driveshaft to move slightly in and out of the tranny for suspension travel. Easiest way to check the travel you may need would be install the driveshaft into the rear end, remove the shocks and then get someone to bounce (gently and slowly) the back of the car as you take your measurement for travel at the tranny or wait from someone else to reply with an amount of travel to allow for.
