TunerCat does have an $8C and $8CA for those trucks.

But I have an $8C but it came in a folder marked "8C 1227748 90 2.5TBI L68" and $8CB that don't work...

EDIT: From the ADX/XDF Lookup "16245358 27C512 $8C 95 C & K Truck, Van, 4.3L $8C.xdf Maybe OBDII ? A309.ds or A217.ds ?

So what PCM is it?