before you spend any money on stuff, I would recommend the following process to truly zero in on the problem (understanding that the pinion seal is shot but replacing that is a more involved process). Trans leaks have a way of disguising themselves and presenting as a different source than what they actually are.
Take the skid off, and with brake clean and paper towels get the trans completely dry. Pay particular attention to all the orafices: dipstick tube, cooler lines, shift selector, neutral safety switch, torque converter solenoid plug etc. Basically everything above the pan gasket. Virtually every trans leak will eventually run down to the pan gasket and make you think that's the problem. But also clean around the mating surfaces and the front/bottom of the bell housing, and the stuff on the transfer case like the speedo assembly, output seal etc.
Once you get it totes dry, jam paper towels in & around each component. You may have to get creative. The idea is to have the paper towel catch the drip before it has a chance to run, so you can isolate the source. If there is a better method than this to track down a trans leak, I wish somebody would post it here. I've had great success with this, and each time it has led me to to something that I didn't suspect (dipstick tube & selector shaft seal). Once you get each area wrapped in paper towels, let it sit for a good while, then come back and investigate.