Not sure on stock length, but measure from U-joint centerline in trans, to U-joint centerline in axle as the car sits on its wheels. That's the length you need. Even if you find out the stock length, I would check this anyways to verify it's correct.

I had a guy in Elkorn Wisconsin (Elkhorn Driveshaft) build one to order per his measurement technique, and it fit perfectly. The brand new driveshaft, came with u-joints both ends, and was $185. I thought it was a bargain, AND he was a nice guy too.

Don't mess with used ones if you can help it, you don't know if they are out of round, or bent. In my case it would have cost more to determine if it was ok, than to just build a new one.