Switching from manual to automatic? 1977 Ford F100 truck?

Hello I'm going to switch manual to automatic, I just need to know the cost estimate if I had it done professionally. I know it will be expensive but I want this truck only.

Around 5000 dollars

You probably pick up a C4 or C6 in working order for around 200-500. You'll probably want to have it rebuilt, so that will be another $500-$700. You'll need to get the proper steering column, you may or may not need to have the gauge cluster replaced, and there will be other auxiliary bits and pieces. Figure around $2000-$3000 for the whole job.