Squeaking usually means a lack of lubrication, there is a good chance the oil galleys are plugged.. Or the oil pump is weak and not supplying enough oil to reach the upper portion of the engine... OR, the bearing are worn so bad all the oil escapes before it reaches the top end...
I could go like this all day, without knowing more of the condition of the engine it is impossible to give you one correct answer..
1993 Thunderbird LX 3.8 AOD. My toy
1997 F-250 HD Extended cab, long bed, 5.8L, E4OD.