Mine is a six speed so not an exact comparison but here are some temps.
I use the required Texaco mtx fluid. I have had a trans temp gauge on for about 13,000 of my 23,500 miles. I just installed fast coolers recently.
Prior to fast cooler installation 95 * OAT no load 75 mph sustained interstate driving at about 1000 feet above sea level
I consistently saw 175 degree transmission temps. I saw a peak of 195 degree under same conditions with a 13,000 pound load 5th wheel trailer + tractor on a relatively short steep grade on I70.
Post fast cooler installation I have seen consistent 155 degree transmission temps with a peak of 160 degrees. 90 *OAT
no load 75 mph sustained interstate driving as above. I have not yet pulled a load to compare post fast cooler. It appears that the fast coolers are good for 10 to 20 degrees cooler temps at least initially.
I have kept spread sheet records of trips of temperatures of my differentials, transfer case, transmission and oil temps.
Its too long to post but if you want to e-mail me I'll try to send it to you if you like. I have some mountain driving in Wy, CO, SD as well as flat land interstate loaded and unoaded.