1988 chevy c1500 diagnostics

[markn]

New to using diag sw. Old to working on a 1988 chevy c1500 with a a 5.7tbi. Trying to diagnose some ignition/running problems. I downloaded tunerpro rt, checked with aldlcable.com for a 12pin to usb cable. Will I gain any knowledge of what the truck & ecm is doing or am I wasting my time & money on it? Also, I have a 2006 gmc sierra 2500hd 6.0 gas (odbII). ALDLcable said they don't have anything for it. Will tunerpro work w/ the odbII in that '06 and if so, where/what cable would I need?