Slick 60's

Know this is a regular question but cant find the thread. I badly need a powersteering in my F250 Twin I-Beam -66, but dont know the parts to look after.

Here's a good tutorial on a power steering swap for '67-'72 trucks ('66 would be the same).
http://www.fordification.com/powersteering.htm

Here's how to modify the steering column.
http://www.fordification.com/steering-column.htm

Powersteering is very uncommon on these vehicles. It probably suffers from worn kingpins and bushings. This will make the steering much more difficult.

Easy. You need:
'70 - '79 PS gearbox with pitman arm and lines
Brackets and pulleys to fit the engine and PS pump. (You can use any PS pump from '70 - '86 if the brackets and pulleys fit the engine. There are several types of external pump design, so you have to get the right brackets and pulleys.)
Shortened ''65/'66 steering column or a '68 - 72 column (A '73 - '79 steering column can be made to fit too with a little more work).