The difference is pretty amazing.
Also, just to relate my experience since I just got done with it - in one of those write ups the guy says it only took him a couple hours working at a leisurely pace... it probably took me 8 hours between two days. Part of that I'm sure is that I'm a noob when it comes to a lot of this stuff, but I also ran into multiple issues
- radiator apparently not having a petcock valve, so I got fluid everywhere when I drained it by disconnecting the lower hose. I did have a bin underneath to collect the fluid, but removing the hose didn't go smoothly as I had imagined.
- needing to replace hoses that had been basically baked to the old heater core over time, and trying to find the replacements
- not having all the tools I needed before hand (I had a big enough hole saw for the new hole, but needed a smaller one to cut a wood circle to use as a guide inside the old hole while I cut the new one)
- trying to figure how to get to the clip between the housing and the body to get it disconnected, that damn thing took me forever.
- Also, having a second person helps quite a bit when re-installing the housing.
So just be prepared to have your jeep possibly out of commission for a little while.
'89 Islander - 4.2, MC 2150