Trans cooler

If you experience too high a trans fluid temp consistently, then install a cooler along with a temperature bypass valve for cold operation to help it warm up. Beyond 210 or 220 F is getting too warm, IMHO. My son's '65 Cuda and 340/904 shows the trans temp getting beyond that temp range on long, hard, high speed climbs in the mountains, in fall temps in western VA. We'll watch this summer to see where it gets and make a final decision on adding a trans cooler, or not.

The one issue for too cold that I am aware of is poor shifting.