i just finished my swap fron c4 to th400 and i want to use my existing temp gauge for the th400. My c4 had a small plug in the pan that i was able to use but the th400 only has a drain plug so are there any other options to get a temp gauge on this thing?
In the pan, if it's aluminum just drill and tap steel just weld in a bung. The sender you show looks like an Autometer sender. If you don't want to drill your pan drill your drain plug. You can then put the sender in the middle of the drain plug. If you don't want to drill it they sell drain plugs with a 1/8" pipe plug in the center.
Having the temp sender in the cooler line or case is fine if you want to watch the gauge while driving to see the load on the fluid.
I have one in the pan and one on the exit line with a three position switch to change input. The one on the line uses a bracket that is external to the cooling line. It puts the sensor up against the line. It needs to be a hard line, but I think it is brilliant. It is probably not 100% the same temp as the fluid, but pretty close.
I think I see 160 in the pan and 210-220 on the line. I think you will see trends quicker in the line as you get more of an instant feedback from the pump. Rather than through the line, cooler, then line, and then there is the themal inertia in the pan to overcome with mixing, etc. Just my guess. Though with my setup, the line needs to heat up before the sensor will see it, so there is more delay but I bet it is negligible.