My standard response to that is...

If you have to ask, you can't afford it. But, by the looks of your signature, you can't afford to not do it. It is so nice to be able to drive up a hill on a freeway and not have to listen to a 4 cylinder at 5,000 RPM's in 3rd gear. That bad part for you is it will be harder (meaning more expensive and labor consuming) on your solid axle frame than it would be on an IFS that came stock with a 3.0.