Transmission Cooler Question

The 904 transmission gave up on us and is at the shop being rebuilt. The shop recommended a trans cooler be installed. In the past I've always installed trans coolers (maybe wrong) and eliminated the fluid from running through the radiator. I'm now older and with the good old google machine, see that running it in conjunction with the radiator cooler is the proper (?) way of installing a trans cooler?

My question is when installing this cooler should it be installed in line with the radiator?

The car is a 70 Dart( daily driver), 318 stock rebuild with a edelbrock intake and 4 barrel carb, with a 27 in radiator (aftermarket non aluminum) with a clutch fan. We do live in SoCal and we've already seen 105 degree days here this year and with traffic, things do get warm.

Here is the link to the cooler we are installing:
https://www.amazon.com/gp/product/B000C3BBEY/?tag=joeychgo-20

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