Installed B&M gauge according to directions with the t-fitting in return line from auxilary cooler back to trans. I also want some indication of how hot the tranny actually is. So I want to have another sender from the transmission and use a switch for the gauge. Other posts mention a pressure port plug that can be used for a sender. Where is the port and what size threads. Does it matter whether or not the sender is a B&M sender or can I just use any oil temp sender with the B&M. Is there any possible problem with using this port for a sender, like restricting fluid flow ??? What is actually being measured at this port, the fluid as it is going in to the trans, or after going through converter or what ???