Thoughts on the factory OE auxiliary trans cooler that came with factory 426 Hemi cars.
Will it provide sufficient cooling for a mild street Hemi car with a reverse manual valve body, ~3,000 stall and 3.91 gears with 28" tall tires?
Thanks in advance for any input.
Any really good aftermarket trans cooler with threaded fittings suggested if not sufficient?

I would want more than that. As we know heat is the killer & I'm sure you have alot of dough tied up in the trans as well. there was something posted way back about a "stacked plate" type being superior, You might Google it.

The "stacked plate" coolers (more of a semi-truck product than a car product) are more durable for sure, but I'm not sure if they cool any better than the regular "tube & fin" type.

In my opinion, a stock-style transmission cooler is nowhere near enough cooling for your stall/gears. I suggest you at least consider one of those setups that comes with its own cooling fan(s). If you keep the fluid cool, your transmission will lead a long, happy life.

hi

you can have too small of a trans cooler but you can not have too large of a cooler !

stock hemi had 2800 stall converter , you might be fine with it .

With your set up it should be fine. I've ran a 12 1/2 cr Hemi with 4.30 gears on the street using the factory cooler.

If you have an IR gun, hit the trans pan after several different drives and see what temps you are getting to. This is what the trans sees. We all have our opinions but you can't argue with real world data. Then of course you have to decide what is too hot for temperature.

The factory cooler should be enough, but if you want more some 70s Dodge trucks had external oil coolers that bolted right in.

Thanks everyone for the input! Much appreciated. I'll proceed with stock and update with my findings.