GEN 1 Vacuum System 101?

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Dane

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Admin, please delete this post. Duplicated in both Engine sections
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I want to educate myself a bit more on the vacuum system - specifically regarding the IWEs since I've had my share of issues.
I'll list out the basics I understand and I'm hoping a guru can expand on them.

Things I understand.
Engine Vacuum is used to maintain 2wd by retracting/disengaging the IWEs.
I understand how the IWEs work and carry a spare. I've watched a video about how to replace one, but haven't myself yet.
I understand there is a check valve (can I get a part number?) and a purge valve (part number here too please?). I'd like details about these. Is there one of each per IWE vacuum line? I assume the check valve is simply a one way valve, though I don't quite understand what that accomplishes in this application. Is the purge valve basically the actuator which engages/disengages vacuum to that line? What other devices are in play for an IWE line itself.

Little bit of back story. I've broken two axles and toasted a couple IWEs - but it's ALWAYS the driver's side. Last time I was out playing my driver's side IWE started slipping out and I was losing 4 wheel drive. Luckily this was literally at the end of my trip on the way back to camp. Dealer tore it down and found no issues. I can't make it happen again, though I suspect that under heavy load it will. IWE looks fine, supposedly vacuum is fine. I almost wonder if whatever actuates the vacuum might be kicking on a little when it shouldn't be (in 4wd) and putting just enough vacuum on the line that when under heavy load it disengages.

Due to all of this entertainment, I feel like it would benefit me to have a greater understanding of how this system works, so thanks in advance!

Also, sorry, this should have been under the 6.2 section and I see no way to move nor delete it.
 
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