Goinsolo

Hello all,
I have an 88 Ford Ranger with a 4cylinder. I plan on swaping it out with a a 3.8 liter 6 cylinder. I have the matching tranny and rear that came with the 6 along with the computer. Basiclly I am putting in a whole new drive train. Has anyone done something like this? Can you think of any problems? All and any of your input would be very helpful. Thanks!