I run a Flex-a-lite 4232 (though I don't think they make it anymore). It is rated at 32,000 GVW, and is 10.5" x 21" x 1.5". It outperforms any other trans cooler I have tried. I first ran a small tube/fin rated at about 15,000 GVW, and my trans temps never changed at all (this is why it is important to have a gauge so you know if it is even working). Then I ran a plate/fin (which is supposed to be better cooling capability then a tube/fin) rated at about 20,000 GVW, and I saw about 5 degree difference during normal operating conditions. When it got real hot outside, or I towed/hauled loads, there was no difference at all. The I switched to the 4232 which is a tube/fin rated at 32,000 GVW, and it is by far the best. After installing it, I saw temps about 35 degrees lower then normal during normal operating conditions, and when it is hot outside or I haul a load, I am about 15 degrees cooler then what I usually see. I also installed a larger capacity alum pan (2 qts extra capacity), and that improved temps even more. This 4232, even though it is a tube and fin, seemed to outperform them all, mostly due to its size. Thickness is the key, and the tubes make 6 passes. Most are only 3/4" thick, and the tubes only make 4 passes. Installation was very easy. Most everything you need comes with the cooler, but I did have to buy a transmission line fitting kit (I bought a Hayden part #396 Transmission Line Fitting Kit: $14.99 from my local auto parts store) to make my new connection at the radiator.

One down side of a large cooler though is how much of the radiator it blocks. So air that is getting past it to the radiator is also heated up by the fact that hot trans fluid is flowing through the cooler. So, basically you have less air getting to the radiator, and what is getting there is already heated. But the truth is, even with all this, my engine temps stayed the same as it did before. I've never overheated, even in the summer months when it can be in the upper 90's/low 100's in some of the places I go, and even when I am towing. It also still takes just as long to warm up to operating temp. I basically have seen no difference in engine temps with the larger cooler, but a noticable difference in trans temps (as compared to no cooler, and the smaller coolers).

I agree though that a cooler with an integrated fan and thermostat would be a very good setup. Price was a little to high for my taste at the time, but they are probably the best way to go and I plan to switch to one some day. More complicated to install too since it requires electrical wiring too, but hardly difficult. It allows you to have effective cooling while your not even moving, or moving very slowly, which is a definitive advantage over the coolers with no fan. The main problem I have heard about the coolers with fans is finding a good place to mount them. They are thick, so they don't fit well in front of the condensor and radiator, but you still want them to be in fresh air.

 

The one I posted is the biggest I saw. I don't think they make the 4232 anymore.

 

Check out part# 45321. Looks like the same specs as mine, just new part#.
http://www.flex-a-lite.com/auto/html...l-coolers.html

 

Check out part# 45321. Looks like the same specs as mine, just new part#.
http://www.flex-a-lite.com/auto/html...l-coolers.html

 

Double post ftw!!!!

 

Ya that was wierd I only hit "Post" once.

 

You don't need the heavy duty cooler b/c if it works too well it could damage the tranny as well for our trucks the regular duty one is the best bet, especially since your only towing a 20' ft trailer. Uhaul only has them for 46.00
http://store.uhaul.com/Transmission_...mission_Cooler
Instructions are included as well as all hardware.
BTW the factory tow package on our trucks included one, it's located b/w the radiator and a/c condenser. Just a heads up.

UPDATE: Uhaul's heavy duty one is 81.00 and its still not big enough to do any harm and will give you plenty of coolong.

 

I think I will go with the 4126 cooler because, although it only has a 3/4'' thickness, the tubes make 8 passes. Its a 10'' x 20'' and is rated for 26,000 GVW. I cannot spend $100 just on a cooler right now and this one seems to be the best for the money. If it does'nt work that good, I will buy another in the future when I have more $$$.

I'm going to also be running an external filter (like dhvaughan's), no check valve, and a temp gauge.

Can somebody give me the P/N for the WIX filter, please?

 

Well, if by doesn't do any harm you mean it doesn't work at all, then by all means get that cooler. I have tested plate coolers of that same size, and they made absolutly no difference in trans temps. You will not damage your trans by having temps too cool, escpecially when we are only talking about 20-30 degrees below normal. If you ran with trans temps at 50 degrees all day, then ya, you might have an issue. But keeping your trans temps in the 160-180 range will not do any damage, and will help the life of your trans.

 

By too big I mean't the ones so big they require any extra tranny fluid than normal w/ the ones at uhaul they don't require any extra at all. They look pretty mush just like the stock one on my truck.