John,
No, we did not install the differential cooler at this time as the majority of the races are sprint races of 30 minutes or less. If we ever consider doing a race that lasts longer than an hour, i.e., 12 hour or 24 hours of Sebring we will need to install a cooler. At this time have not seen any diff
oil showing signs of excessive heat. We are running a 3.54 Dana currently. If for some reason we went with a higher gear ratio and were spinning the gears faster we might consider it as well.
Jim