Considering magnum swap

if you used the 5.2 and swapped to a 5.9 later you would need the 5.9 pcm unless the 5.2 pcm could be reprogrammed for the 5.9. The difference between a stock 5.2 vs 5.9 is about 20 hp, but there is quite a difference in torque.

Found this on another forum.
The 5.9L is rated 245 hp/345 lb-ft and the 5.2L is rated 225 hp/300 lb-ft