Why bother? The factory cooler kept the transmissions pretty cool. I have a digital transmission gauge on my E-40D transmission on my F-53 based 17,000 pound motorhome. It pretty much stays around 180 F but will increase to about 200F on a long grade. I also have the 460" engine.
What I did was buy a digital transmission gauge at JcWhitney.com and installed it on a 1985 GM motorhome, by removing a pressure tap fitting that is 1/8" NPT. When I sold that RV, I bought my 97 Bounder, and installed the sensor in a similar location, by removing a 1/8" NPT plug. The gauge sits pretty much still once it warms up.
On the 85 GM, the transmission overheated all the time, until I installed a really huge cooler, and then the engine even ran cooler!
JcWhitney.com Then search for digital temp gauge.
I just bought a 2001 E-450 based shuttle bus, and it has the 6.8L V10. I installed a "Edge" CTS digital meter. I can monitor all kinds of things, including transmission temp, engine cylinder temp, horsepower output, ect. Right now I am monitoring RPM, horsepower, MPG and MPG coach.
The transmission ran so cool, that I am no longer concerned with it's temperature. Perhaps if I take it into the mountains, with a heavy load, I will watch the trans temp again? The Edge CTS will plug and play with any 1996 or later OBDII car or truck. Sorry that it will not monitor yours. Then again, at $310, it is a lot more than a few digital gauges that it can replace on a newer vehicle.
Good luck!
Fred.
Money can't buy happiness but somehow it's more comfortable to cry in a
Porsche or Country Coach!
If there's a WILL, I want to be in it!
I havn't been everywhere, but it's on my list.
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