Well.... if they say it doesn't fit chances are it doesn't. Kind of not excited about trying to fit it via mods.
Options - spend 15-20 dollars, get it, if it's not right, give it to somebody else.
Maybe you could somehow get the lines out, -if- they're the right length (probably), and put in existing grommet. I think that probably wouldn't work.
Or, ask my shop, tell them, I've isolated the leak, can you get the part & put in? Swapping in the new part should be fast; finding the problem is what's time consuming.
Here's the thing, whether heater core turns off or not isn't that huge a deal. It probably helps a little. Having the recirculate door working is fairly important. I mean, everything is important in terms of saying "everything works". Problem is right now I have a short line going black-black at the firewall, but if it falls out, you lose all functions for the vents (no vacuum at all). Now you'd know that right away, and you don't have to take things apart to put it back together, and because there's vacuum on it, it's not likely to fall apart, but it can, and it's not really kosher.
If anyone can locate the right part I'd sure like to know. Bugs me it's only 1 year off but gen changes can be a killer.
Also option to ask junkyard to pull one and test it make sure it's good, probably would cost more than the '98 part new.
Also option to pull the part from my truck, try to find the leak and try to fix it but that's not really how I'd like to go. You could imagine if you find the leak, put vacuum on it, put some cement... might work, but if it pulled the cement into the tube it'd plug it and they are tiny.
Just kind of thinking out loud... best option is find the freaking part new, I think second is junkyard, if it tests ok, should be ok.
Out of all this though I really learned how the system operates and how to find leaks. If you have that 3/32 ID rubber line and a few golf tees that gets you a long ways as to doing tests, the 3/32 fits the outside of the nipples and the inside of the female side (on the connectors / connect blocks) so you can set up different scenarios to isolate things. Didn't spend anything except under $10 for the tubing (and a bunch of time). So the project was 'successful' in terms of finding the problem.
I'm pretty sure rest of stuff is ok. If I run the truck, then turn it off, then turn the selector to "Off", it activates the door and holds it (I don't know how long, but, a while). You can even switch from Off (with engine off), let it close (or open depending how you look at it) partway, switch back to Off, it stops. That tells me except for the known problem, it holds vacuum.
Thanks for all the help and encouragement, nice to not be on my own with this stuff.