if I wanted to swap a 4.0 v6 to a 302 how much would it cost and what would I need to do

 

Welcome to the forum

I would budget $3,000

You would need to find and buy a Ford Explorer with V8(302/5.0l) with body damage but working engine and trans.
You will be swapping over pretty much the whole drive train, computer and wiring from Explorer to Ranger
Year of the Ranger matters here and of the explorer

Explorer V8 has the lower intake which is needed in a Ranger engine bay
All explorer V8s would be automatics, if you want manual trans then you can use the M5OD-R2 5-speed and also need V8 computer reprogrammed

You can see the work involved in some of the articles here: The Ranger Station - Conversion Index

You can also search the For Sale adds, locally and nationally
You can buy finished Ranger V8 swaps or partially finished swaps
This will give you an idea of what you should expect to spend