I'm sure your son loves it. What a clean 15 year old truck. I read your story and it reminded me of my old 2002 Infiniti QX4 (SUV) ownership story. I bought it used in late 2004 and drove it until 2011 when I finally sold it (with about 60K miles on it). The SUV (metallic white) was in immaculate condition when I bought it and I took meticulous care of it while I owned it. It was luxurious, solid, and so enjoyable to drive. To this day I am so sorry I let it go.
I hope your son enjoys it going forward and takes good care of it as well.