That is the same PCM that is in my 93 K1500.

.adx is for data logging. This is used to monitor the engine when it's running.

.xdf is for editing the .bin file (PROM PROGRAMMING). This is used to change timing, choke, fuel, AE, PE and dozens of other parameters. Reprogramming the .bin file is the ULTIMATE TBI MOD! Reprogramming the .bin file is 100% necessary to get the best possible performance for bolt on engine modifications (vortec heads, aftermarket camshaft, aftermarket intake system, aftermarket exhausts systems, more fuel pressure, and larger throttle bodies). Reprogramming the .bin file is like changing carburetor jets, distributor weights, and distributor vacuum advance.

dave w