towing with a 96 ford windstar minivan

We tow our 2619 sport with a 96 ford windstar minivan 3 liter. On flat road it tow's great but notice a little struggle going up hill's. Does anyone think that this will in time damage the transmission? we hate to buy a larger vehicle if we don't have to.. any comment's would be helpful or does anyone else tow their tm with a minivan?

Yes, in time your trans will over heat. See how much to install a trans cooler at your dealer. This will save the life of your trans.