Potential problem with Isspro gauge, tranny running hot

[smooth]

So, I installed Isspro gauges for the first time in my 7.3 (I've used autometer in the past). The sending unit is mounted in the test port on the driver's side of the E4OD. After installing my engine, I noticed my tranny was running hot. In fact, on a trip up to northern Va, it would stay around 205-208 at 70 mph. I never had any slippage issues or anything else that indicated I had cause for concern. I also made sure my torque converter wasn't slipping by testing whether in engaged and disengaged while in overdrive.
So, my final thought was to check the new gauge. I took my truck out for a long hard drive, got the gauge up to 190, brought it home, hooked up the sending unit from my Bronco in line on my 7.3 and started it up. The Isspro gauge was reading 190, while the autometer gauge was reading 165.
Now, the sending unit for the autometer was AFTER my B & M auxillary tranny filter (which is mounted next to the radiator). So, the fluid it was reading left the tranny, ran up to the filter, through the filter, and then past the autometer sending unit.
That doesn't seem like enough time for a 25 degree drop, especially while idling in my driveway (i.e. no air flow across the tranny line or the filter). Also, in my research, I read that the tranny fluid leaving the tranny was 25-30 degrees hotter then at the test port, so it would be more like a 50 degree drop.
Can I finally feel confident that it's my gauge and not my tranny that the problem?
Thoughts?

MoMo

 

[argve]

you need to establish a better test for the gauge and probe. Like for example we know that water boils at 212 degrees F, so can you take a pan on the stove get it boiling and then take the probe and place it in the water to see what it's reading? That would tell you if it's reading correctly.... And since we are looking for temps in that general range it would be a good test I would think.

 

[PwrSmoke]

I have had three sending unit hooked up at the same time (with a selector switch to go between the locations) and I could believe a 25 degree drop between the two locations you mention. You could still have an inaccurate gauge, but here's how you might test.

This is just an extension (or perhaps clarification) of what argve said above, but put both senders in the same media (hot water) at the same time and see how they read.

 

[crashnzuk]

You could swap the senders location for one another and see if you get the same results.
Travis..