Actually, they are both the same pressure--except for whatever resistance in in the circuit. I believe the lower connection is where the fluid is pumped out to the cooler, if that is what you are asking. But ckeck your manual to be sure.
The top outlet "feeds" the cooler and the bottom inlet is where fluid comes back to the trannie. Too use to laying on my back, briefly got up/down/top/bottom mixed up--also looked in my manual.
Just as Bruce and Clay described, Mosher has a picture of trans cooler installation to show this. Its what I used to install my trans cooler. http://www.gnttype.org/techarea/images/Cooler.JPG
So the trans fluid in this diagram would go through the aftermarket trans cooler via the top line, then through the stock radiator trans cooler, then return to the trans on the bottom line. Let me know if I am wrong.
I'm going to bump this thread because I'll be buying a trans cooler soon. Probably buying this one: http://www.summitracing.com/parts/BMM-70268/ being that it was recommended as the best for the money and easy to install (from an older thread). I'll take input for other trans coolers though.
Is that install diagram from gnttype's site right? And tim87tr's question never got answered - is that A) the way it would be...the trans fluid goes into the external cooler first, then into the radiator, then to the trans? And B) is that how one wants it? Wouldn't the fluid be cooled more if it went into the radiator first, then into the external cooler, then back to the trans? Wouldn't it be best to have it go through the external cooler last, being that the cooler the better?
That diagram confuses me. The left arrow shows the flow going back to the trans, but the arrow closest to the radiator appears to be showing the flow going into the radiator. The question is, is the line that connects to the top of the radiator going out to the trans? If the top line goes out the rad, then that would be the correct configuration; rad first, then cooler.
Okay, so do it as per the diagram...he just had the arrow in the wrong direction.
And I have an RCJ FMIC. I guess I'd still mount it in front of the radiator (the lower left corner), and behind the FMIC? Not really any other place to put it...