get ready to spend some big bucks!!
there was a GB over on XR-underground.com for the oil cooler, the package was like $600...and thats a hookup!! didnt even come with water inlet casting!
concerning the trans cooler, just get a stacked cooler from hayden, should run you ~$60 at pepboys. it will also be larger than the OEM cooler.
some of the desert guys sell their hitches for around $150, so just keep an eye out!
concerning the alternator...do really know what to tell you on that one. i've kicked around the idea of getting one too, but havent really needed it.
for the harnesses and such, a few have suggested that its a pain to add the OEM wiring. there is a towing DIY around here somewhere that has a few good places to pick up the required wiring.
hope that helps!
Truck has been sold...but i'll still lurk cause i'm obsessed w/ tacomas!!
1 - Want LEDs swapped in your cluster, radio or steering wheel in Denver, see here!
2 - My build thread here