Mag-Hytec has a sender bung. I had my ATS pan drilled and tapped and I had my deep pan (steel) drilled and bunged.
The pan guage well read approx. 20 degrees lower than the stock guage. This only gives you a indication of the return fluid cooler efficiency. But once every thing gets heat soaked you'll find all the temps pretty much unite.
Do you need one? No
T tranny temperature guage is more needed for a vehicle with NO stock temp guage. I basically installed one on my truck to fill a third hole to use a A Pillar triple guage pod.
Nice bling is cool but not necessary.