Stupid question time...driveshaft tech?

[Critter]

I needed a new front driveshaft for my Blazer and I ended up finding a set of front and rear online. I have a 6inch lift and I knew that the front would probably have to be lengthened. As expected the front shaft will extend all the way and just barely reach. My question is can I take the short end off of the rear shaft and put it onto the front? I’m not sure what the proper name for the short slip-on end of the shafts are called, but the rear looks to be at least an inch longer than the front. Keep in mind I rarely take my K5 off of the pavement at the moment, there are still too many things I need to fix. Eventually I would have a shaft made that was the proper length, but for now is there any reason why this swap wouldn’t physically work? I realize that I run a risk of over extending the shaft, but I really want to put something in there for now so I can make sure all my 4x4 parts are working properly.