I ended up ordering a Kenwood Excelon DDX9905S. It was listed new on Amazon for $125 less than a reconditioned one on Crutchfield and I got an Authorized online reseller to price match. I can order the wiring kit from Crutchfield and still come out ahead. It has some DSP capabilities. I had planned on getting a DSP equipped amp but you are right, this is an older truck.
Skip a dsp if you’re just going to put in a passive comp set. That amp has plenty of tuning capabilities. I don’t know if you have to do the resistor to keep Ac going like the 2003+ But I’d Bypass the harness and go independent to an aftermarket amp. Save a lot hassle. The gmd 9705 amp is a great five channel amp and super compact. You can put a small sub over the wheel well right over the factory sub in amazon sealed enclosure to save space and keep it cheap.