James - the life expectancy of a core plug is all over the map. It has much more to do with the prior maintenance of the cooling system contents, rather than miles traveled or years on the planet. If there has been a healthy mixture of coolant & water against their backsides, they can last almost forever. If someone has been running virtually straight water, expect them to be rusting. When a head is off (or an engine is out), I am always a fan of replacing them at that time. It would have been an excellent thing to do when you had the JY motor out of the car. Now, not so much. They corrode from the side you can't see. The symptoms of failure range from slow seepage [in most cases], to fairly sudden significant leaking [rare].... what is your estimate of the life expectancy of freeze plugs?
Wagon hatch wiring harnesses are a continuing saga on this board, due to their penchant for failure in the short run between body and hatch, where they have articulated a bazillion times over the years. I realize that people have different talents and hold varying opinions. Here again is my take on repairing that harness.
They can and have been repaired in a very professional manner [by me] WITHOUT removing the harness from the car.
If one insists on removing something from the car in order to get a longer run of harness to work with, I whole-heartedly recommend removing the BODY run, while leaving alone all the connections buried down inside the hatch. Below is a photo that illustrates my point.
But first, a quick explanation about the picture.
This is a photo I posted here earlier this year (I believe in the main "what did you do to your 2nd gen today" thread, not the wagon one of the same name). A few days before my daughter's good friend was flying into town to be shown all the local sights, I blew out the back window in her wagon by backing into it with the RV. The glass company wanted $800+ for a new rear window, so I simply took an entire spare hatch and painted it to match her car. As is often the case, masking took much of the time, but it wasn't really a big deal for me. As part of the project (and here is where the payoff is), it was necessary to unplug the hatch harness. I chose to unplug the BODY run, and if you look closely at the photo, you can see why.
If someone needed to repair this harness, and wanted a longer run to work with, why wouldn't you just do it this way? One plug and done.