A friend of mine totaled his 3/4 ton pickup because he tossed the two piece driveshaft and went to one loooong shaft. He pole vaulted off the freeway coming down a long hill. I'd talk to the folks at the driveshaft shop, may need a two piece.

It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed