1978 F100 Power Steering Conversion

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I have a 1978 f100 w/ a 300ci 6 cyl and 3 speed column shift. I am trying to install power steering in it, and have all the parts(I think) The power steering gearbox is longer than the manual, and I'm wondering if the steering column has to be replaced also, along with anything else. I thought this was going to be a bolt on conversion. Can anybody help me out? Plz email me an answer if you have one, much appreciated - [email protected]