fix the ranger? my buddy used to have a 4.0 ranger and I dont think his gas mileage was that stellar. If your f-150 trans will bolt to the 4.0 then leave that in place with the trans crossmember and just fabricate some motor mounts that locate the motor in the right spot to utilize all the drivetrain parts in your current truck. If it is an automatic tho it will a bigger pain in the ***** to make it shift properly. I dont think id do it but its your ride, just be sure and post some pics if you do decide to do it.