Battery drains in three days sitting

I got the truck a year ago.

I ran a parasitic test on it and showed only a 0.03 drain fully connected on a 10A setting.

I pulled the alternator wire from the firewall and did a diode test and the diode was fine and the meter still showed a 0.03 drain.

I pulled the instrument cluster wire from the firewall and got a 0 reading.

I put just the alternator wire back on the firewall and it came back a 0.03 drain and if I pull the 20amp fuse that's attached to the main fuse I get a 0-0.01 reading.

So this is where i'm lost. I hear if your drain is 0.05 or less your good but this battery will not stay charged over several days sitting.

I checked the battery. Over night trickle charged and let it set a few days not connected to anything and no battery drain.

What could it be that I am missing?