Company I used to work for was a GE distributor. I have done hundreds of these over the years. The easiest way to get the rear Male part / shaft onto the rear of the drum - I had a jig made for this. I would insert the shaft into jig, then line up the rear heat shield onto the jig. It would line it up perfectly, then lay the drum on the top. The weight of the drum would push down, and then you could screw in the three screws.
Unfortunatly, that jig is buried somewhere in my warehouse (garage) and I can't take a pic at this time. Without the jig, the secret is to use 2 straight little pics. I would tape the shaft onto the heat shield, then lay the drum carefully on top, then line up 2 of the screw holes and screw in the third. Once you get the one screw in, the other two go in easily. You are right. GE has a Simple system (that is until they started having Frigidare build their dryers for them), and you don't really have to change them that often.