I picked up an LS1 aluminum driveshaft but gotta change the front u-joint. It appears to be the original joint in it now. Any special precautions to take or just heat it up to release the nylon material and then remove it the same as a steel shaft? I'm guessing it's better to use a press than a hammer?

 

You pretty much answered your own questions. It's really no different than a steel shaft except that you should use more caution and finesse when changing it on an aluminum one. A press is definitely better than a hammer, or a bench vise with wide enough jaws and the right size sockets. I really messed up once doing an aluminum one. I was using the big c-clamp tool made for control arm bushings, ball joints, u-joints, etc., along with an impact wrench to drive it in quicker. Once I had the cap fully in on one side, I put the snap ring in to hold that side in place while I drove the other cap in place with the tool and impact. One of the pencil bearings had fell into the bottom of the cap on the side that was already in. So when I used the impact to run in the other cap I couldn't tell I was using too much force to seat the remaining cap, and it blew the snap ring right out of the land it sits in, taking most of the aluminum with it! I was lucky that there was just barely enough of the ring land left to where I was able to rotate the snap ring in a position where it was able to seat in what was left!