Sadly Jake, I would start with the local junk yards. I think its noble that you want to find your fathers old truck, even though he couldn’t have like it that much since he sold it in the first place.
Fifteen years is a long time, and many things have provably happen to that old ride since then. If it is even still running unless someone took real good care of it its most likely in rough shape. I have a feeling that next time you crack open a beer, that beer can use to be dads fender.
If you live in Connecticut and see the old beast sucking up gas while belching out fumes around town, let Jake know.