what reason for a 4th isolator?

[F3BZ]

i'm curious about the tapped holes in the top of the trans case on a g5m that look like there should be a stud in them. a little research shows that the 323 GTX 4WD trans had a 4th motor mount attached to the top of the trans case and that in turn attaches to a body bracket. looking at images on the web shows a difference in the position of the holes between the 2 trannys but it's still a similar triangular pattern. the 4th motor mount is still available from mazda. i wonder what benefit this might have or what it does. seems to only be on the 4WD turbo car but would there be any reason to look into this on a hi powered FWD app if it happened to fit the tap pattern on a G trans?
here is a pic of what i believe is a GTX 4WD trans showing the mount. i wish i could've found one showing it in the car attached to the body.

[shorestiva]

It's not just on the 4wd drive models. Iirc bp escorts and protege had that mount too.

[skeeters_keeper]

Yep. Not sure about the v6 cars but the egt and protege deff had them.