Radio wiring harness for Isuzu
Thanks for the advice hitnrun74! I found this while researching on wiring harness. There's another one here, but I think the former would be the correct one.
Two wiring harnesses are required to complete the installation-the Metra Isuzu wiring harness described in the first link above, and the Metra radio wiring harness that applies for the specific aftermarket radio to be used. Total cost of the 2 harnesses is about $20.
Nice finding for those like me considering an aftermarket radio but trying to avoid install complications and wiring mess.