Drilled out; pretty good being done on a tailgate with a hand drill, if I say so myself... I used 3/8 MPT to 1/2 hose barbs, so I needed a 3/8 MPT tap which requires a 37/64's bit. Since I couldn't find a 37/64's bit, I used a 9/16's inch bit (which Ace charged a ridiculous amount of money for, I might add) and a lot of torque on the tap.
Tapped. Works best if you hold the cooler like a guitar, so you're pushing into your lap with the tap. And if you have the tap stuck into a 1/2 inch drive ratchet.
Barbs installed. Was afraid to use T-tape, so I used some blue Loctite stuff that supposedly doubled as liquid teflon. Hasn't leaked yet.
Here you can see how much larger the A/C condenser is than the stock transmission cooler.
I tapped into the ATF flow as it came out of the canister on the engine block. I cut the stock metal line (which might prove to be a mistake if I ever need to reuse it) and put a compression fitting with a hose barb on the stub.
The fluid comes out of the canister, and into a hose that I ran along the passenger side fender.
And then the hose enters into the barb that is on the A/C condenser.
And then a hose leaves the condenser and runs along the top of the radiator to reach the stock tranny cooler.
And then it enters into the stock tranny cooler, and then the ATF follows the stock return path from there. (I swapped the direction of flow through the stock cooler, so that I could get a larger radius on the line that drops down from the top of the radiator).
A dollar to anybody that spots anything I screwed up on is going to explode in a few miles. (Or who can tell me why my camera keeps acting like it's been smeared with KY.)
1990 D-250 Regular Cab: Tweaked injection pump, built transmission, a cataclysmic charlie foxtrot of electronics, the most intense street-ran water injection system in the country, and some more unique stuff.