that's weird, because i earlier today came upon this article on fourwheeler's site while researching something else
http://www.fourwheeler.com/techarticles/129_0311_transmission_temperature_gauge/
it's about what you're doing using that same location.

they list some suppliers with telephone numbers and website addresses; maybe they can help. or maybe your gauge's company can help?

or just take out the plug on your trans and match it?

1992 sohc trooper 3.2l v6 automatic . . . as is

i love a good intermittent electrical challenge. . .especially when it's someone else's.