I've been having issues with the charging system on my 2005. The battery was 7 years old, so I replaced it. Now, the battery light comes on dimly (and flickers) when at low RPM. I am thinking alternator. I replaced one on my 2002 F150, but haven't done a 250. How hard are they to get to and replace? This is on a 5.4 gasser.....

 

Alternator is easy to change but if it was me, I would test it with a multimeter first before throwing money at it and potentially swapping parts unnecessarily.
Also clean and tighten all the grounds and thoroughly inspect all the cables for bad insulation or oxidization at the ends.

 

also is worthwhile to check the belt/pulley/idler for tension

 

most auto parts stores will do an charging system test for FREE....

check belt tension.. and tensioner ... along with the idler pulleys...

bad connections both positive and negative...

its only difficult if you do not have the correct tools.
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