Help! What driveshaft will work?

I have read through Allen's instructions for the 4l60 to 4l80 swap. I am not 100% positive that the drive shaft he mentions will work in my truck. I have a 2004 extended cab silverado. If i choose to go with the stock 1500 hd drive shaft which natively mounted to a 4l80 would the front part of the 2 piece shaft connect to the rear shaft of the 4l60 drive shaft? Or would it be worth me finding a one piece drive shaft and going with it. If I decide to go one piece do yall know of a stock gm drive shaft that will work for my application?

i know the crew cabs DS will work on ext with a 60e so i would think if you can find an Crew Cab with an 80e it should work.