Not supposed to be open although mine was too. I used a piece of rubber sheet cut to shape, made a mount flange to hold corners, cut a small hole, gathered it around shifter with a crimp hose band. Keeps the dirt out. I make my own parts sometimes, usually better than stock. Yes, X175 is the switch your looking for. Shift lever should be firm and not flop around. If it is loose then the ball and socket and nylon washers might need eyeballs on.

 

Finally got back into removing the rear access panel under the trans shifter, and found a very pleasant surprise - the harness from the switch (X175) was rubbing on the driveline brake drum so lightly that it had taken the insulation off one wire -without cutting any wire strands! I had wondered how my moving around in the seat had also triggered this chime...
So, tie down and reseal the harness should fix that. Working on a lower boot for the shifter now - I've found a few options in my parts stash that should work great -wondering if a grease fitting (on a hose to be accessible ) would be worth the effort with the tendency of this shifter to seize up from lack of use. The diff lock shaft looks pretty dry where it comes out of the shifter housing. I'll probably drive it a few days before buttoning things up to make sure of my diagnosis.
I'm thinking J-nuts rather than rivets and possibly some strip caulk to seal them to the floor. Still positive...! Russ

 

Here's what I saw, looking down towards driveline brake drum and another shot of the damage done to the wires (you'll have to look real close, because damage was very minimal) Russ

 

It seems my diagnosis/ inspection was the whole problem with the bell - so starting to button up my console and tie harnesses up and found the transfer box solenoid (K161) had the connector broken off flush, but have never had any problem shifting, so it seems solenoid is removed anyway! Just as well, one less worry on the trail! Made a boot (lower) for the shifter and lubed up good. J-nuts for tunnel covers are working well - should have this buttoned up today! Russ