well the stock guage works half @ss so thats why i got an autometer one. so the only drawback is that the stock guage wont work right? if thats the case then it sounds pretty easy.
also, a coolant sender needs to be in the FLOW of coolant to read properly. if it is only seeing the 'alcove' of coolant, more or less trapped in the Tee, it will not read properly. while this would be fine for the inaccurate stocker, your autometer will also be inaccurate.
i chose to run the aftermarket gauge in the stocker's location. there is a rear intake port which can accept a sender. it is not as accurate, since coolant does not really flow past it (as happens with the Tee), but it works (via sensing the temp through radiant heating).
some folks also put the sender in the t-stat neck....if it fits.