If you pulled 4 plug wires off the 5.3L, it would tow about the same as your 5.9 does, it has that much more power. A friend has a 98 1500 with a 5.9L, and he got his father in laws 04 1500 with a 5.3L when he passed and couldn't believe how much stronger it is than his DOdGe. The 4L60E trans is pretty good for the most part, but some have had failed around 125-150K miles, but then again I have seen a lot more with over 250K miles still going untouched. It will probably need a pitman and idler arm for the front end around 150K miles, and the engine may need a set of intake gaskets(seems to be more of a northern problem). The 5.7L engine that GM had in the 90's would flat out leave a 5.9L DOdGe, and the 5.3L will make the 5.7L look like it's only running on 6 cylinders.

I am a GM guy all the way!! I had a 2002 1500 Z71 with the 4.8, towed every where with it, and no issues!! I sold it to a friend with 175,000 miles and I saw it last night when he got home from a trip to NY ith it, It now has 257,000 miles and still strong!
Window motors and wheel hubs are there weak points but other wise was a great truck for me and he loves it!!
I then bought a 2009 1500 with the 5.3 and just gave it to my son, that thins towed my 23 Sea Ox all over with out issue and goig strong right now for him with 60,000
I now have a 2002 Tahoe with the 4.8 I have not towed with it yet but I would not even think about it!

sounds like I cant go wrong with it , cant wait till the 24 th. to pick her up