I have used them yrs back. Some have been good to use others, well it seems like the seal is thinner. Lot of them will melt before you get the solder melted. Nowdays I used heat shrinkable butt connectors. Plus heat shrink tubing on top it them..
Well since you have them out. I would clean the wells up and paint them. I have mine out account the rear is hi- lined. I have painted the wheel wells black though. And I haven't have any issues with the emissions stuff.
I would pre trip your jeep. Check all fluids and hoses an the belt. If your doing I-80 thru Nebraska I am sorry..Give me a shout going thru Lincoln if you need a break..