I'm researching radiators for an LS swap and noticed that several of the "direct fit" rads don't have a built in trans cooler. Is it ok to just run a stand alone trans cooler (for 4l80e) and not have the built in cooler in the rad? car is strictly summer street driven

I'm guessing that you'll not be driving it in the winter, so that should be fine, good luck!!

You will need to run a much larger stand alone trans cooler to make up for the lack of the in rad trans cooler. Liquid to liquid heat transfer is much more efficient than liquid to air heat transfer. A in rad cooler is very efficient at cooling ATF down to cold side coolant temps. Most aftermarket cooler manufacturers suggest to run ATF though the in rad cooler first before going though an aux cooler.

If the stall speed is low and, as already said, the external cooler is large, as in as big as you can fit, then you MIGHT be able to get away with just an external cooler. However, if you're running anything close to or over 3,000 rpm, I'd highly suggest a radiator with an internal cooler AND a good sized external cooler. I prefer the plate type coolers.

As Buick said, most cooler manufactures will recommend to run through the radiator first, then the external cooler. That works best when you have a large and/or efficient radiator. If you find the radiator is marginal, you might need to run it through the external cooler first - to keep water temps down.

Heat is a transmission killer - another way to help keep temps down and to make sure you have good filtered fluid is to run an external filter. I usually change the external transmission filter every other oil change (adds a new fresh quart).

Thanks for the replies. I'd rather run the rad cooler and external cooler - what I have for the 350/2004r. Just seemed odd that on the holley site and champion site, when you search g body ls swap the rad they list has no internal cooler. I'll find a similar one with the cooler