Re: YJ vs. CJ firewall electrical connector
Not sure about the YJ heater motor, I upgraded from CJ to Blazer motor.
All the electrical stuff from your CJ should work just fine. I was able to reuse my fuse box and everything just fine when I put my YJ tub on. I did have some extra holes in the YJ tub where more stuff obviously went through the firewall on the YJ, so for now they are "plugged" with duct tape (great stuff).
I had to drill new holes to mount my CJ battery tray. It was in a slightly different position then the YJ tray. If you have to deal with this on your new tub, then you will have to remove the heater box to mount the battery tray(for access behind the firewall), then remount the heater box.
Hope that info was somewhat usefull.