I looked this morning and there's a transmission cooler up in front of the radiator that spans the entire width of the radiator. (I'm assume it's tranny fluid cooler, anyway.) Is this a stock cooler or did the previous owner upgrade? And if it is stock, where would you put an auxiliary cooler?

Thats not a tranny cooler unless it has the tranny hoses conected to it. that is the AC condenser.. an aux cooler would be installed under the grill in front of the radiator and Condenser

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And so it is. Thanks guys! On a related question, I understand putting in an auxiliary transmission cooler is a relatively easy job, even for someone like me, and one can be had at most auto part stores.

Does anyone know the best size that will fit in front of the condensor? Brand & model number, if possible. Thanks again!

Just measure how much space and purchase accordingly. Your local APS sohuld have a couple different ones.