i came across a borg warner t18 for a great price (free) and was wondering how difficult and expensive it will be to swap it in my '66 f100 300 L6 3speed? is it worth the hassle? any info would be appreciated

 

Not a big deal. Just go ahead and cut a big hole in the floor.

 

Welcome to FTE Davidson, all kinds of good info here, the great thing about these old trucks it that most swaps are fairly simple,,,, I have not done the swap in question, but I am sure someone here has and will chime in soon.