If I remember correctly, put your digital meter on the battery with the engine running and the voltage scale on ac. If a diode is leaking you will read an ac voltage. If not then the diodes are good. You should only read a voltage on the DC scale.
The OP already stated he still has a current draw with the alternator completely disconnected.
I had to go do a little work at the ranch but I'm back now to continue trying to figure out what's wrong here. I went back thru all the fuses and relays and the dome light (DuH!) was causing some draw but I still have .455 amps leaking somewhere. Blade 35 your post mentioned 50 MA is acceptable so it appears I'm still out of range. I had everything obvious disconnected. All fuses,relays, batteries, starter, alt. I guess now I look for anything that does not pass thru the Passenger fuse box and the under hood fuse box. Hmmm I thought everything went thru those 2 fuse boxes (I hate decaf).
Entertaining all possible ideas.
Thanks to all for your help so far.
Can you understand why I nicknamed this truck "Super Duky"
I went and bought another Super Duty this weekend It's a 2008 GAS F250 Lariet 4x4. The 2005 is my first diesel and I got 6.0 voodoo but I'm gonna whip it.
It was mentioned earlier in this thread but are you closing doors and allowing time for everthing to go to sleep? I traced my drain to the instrument cluster 2 years ago useing the same procedure of removing fuses. I jerry rigged a switch and relay rather than change insturment cluster. As I recall,you can trip the door latch and leave the door open and the system thinks it's closed. Pretty handy while removing fuses beneath steering colum. A wiring diagram would be handy but I was never able to find one. The only unfused circuit(s) that come to mind is aux,#4 and #2 in 7 way trailer plug.