5/7" drop-Do I need to change the stock driveshaft?

[Raguemoe]

I ordered a 5/7" drop from CPP (Grand Slam w/disc brakes) for my 67 CST SWB. I ordered the Grand Slam w/3" (f)springs 5" (r) springs and 2" blocks. They said I also needed their rear "shortened" drive shaft with a slip yoke. I wanted to know if the stock 2 pc drive shaft would work. And if not which is better a 1 or two pc drive shaft. I found a guy in AZ that charges $205 shipped on a 1 pc w/slip yoke. I may put bags on the truck in the future.