If this was the first time that your trans puked through the seal then it will most likely be fine once cooled back down. The fix is actually a very cheap new front seal made from Viton (I think that's the correct spelling), the expense is getting to that easy to replace seal, about $400 for a shop to slide the trans back to do it. As long as the torque convertor hub where that seal rides is NOT scored at all the new seal will fix the problem and be more reliable in the same situation. If that TC hub is scored, then you are buying a new TC as that score will chew up even the new seal and leak again.
Expect to pay about $4500+ for either the BTS or John Woods trans, they are awesome units but you have to pay for it. The very good 4R100HD from Ford will save you some money if you decide to replace your still good trans.
As pointed out earlier some '00 7.3's did not have the trans cooler loop in the radiator, make sure that your does or upgrade to that radiator. Also the 7.3 had the smallest trans cooler of any motor in the SD/EX product line, the 5.4/6.8 gasser coolers where nearly double the 7.3's size and the 6.0 was almost twice the size over those. Both the BTS and JW trans come with a new 6.0 cooler last time I checked.
As for an idea to reduce the chance of repeating the fluid leak consider using 2 wheel drive low range for reversing up slopes in the future. If you have manual hubs it is very easy to do, simply leave them unlocked and shift the transfer case to LOW. With the AUTO hubs you will need to either unplug the vacuum actuator switch under the hood that send the vacuum pulse to the hubs or wire in a switch (and replay) to have it cut out on demand of 2WD LOW. The better (deeper) LOW range gear ratio will put less stress on the trans and will build heat more slowly.
