I figure this might be an appropriate place to comment on the fun times anyone would have when trying to replace a heater core in a GMT800 truck. I had to replace the heater core in my 2000 GMC. Out of the available GMT800 trucks, this one should have been the easiest due to the lack of column shifter and centre console.
You need to remove all this:
So that you can get the dash to look like this:
