Trans coolers can be DIY built very easily for $60. In fact most vendors do just that and charge you 3X+ for convenience. I used the EXACT Hayden unit Z1 supplies in their kit.
The pan gasket can be found here
https://www.wittrans.com/parts?type=JR710E+%2F+RE7R01A
I highly suggest adding a trans. dipstick, DIY's are available here.
The change is very easy, especially with the dipstick where you can add from the top instead of pumping from the bottom on jack stands.