I'm planning to replace the engine oil cooler just because of the new build and will also be switching to NPT fittings in order to lose the concern for lines blowing off in the future. I learned the HMMWV oil cooler lines measure 3/8" ID, just like the lines on my truck, but the OD is much larger. I was surprised to find this.
On the transmission cooler, I already have an oversize cooler that was from my wife's old '94 K1500 Suburban. I don't recall the variance in number of plates, but it was significantly larger than what my 4L80E came with.
Now keep in mind, at this time nothing is planed to be done to your heads to stop or control the heat, so your motor will still heat up just as quick and bad as any other 6.x does so plan accordingly, the piston coating helps the piston by deflecting heat away from the piston, the heat will still be pushed into the head.
Now, I'll cover some good points of some of the things I can do in the head area to STOP or greatly lesson heat build up...
I can fill the egr port, ( melt aluminum ), this passage comes off the exhaust runner and every time the exhaust valve opens the heat fills that passage with hot gasses , ie if your egt's are 1100* then that 4" passage is that hot and only heats the coolant for no reason, that passage is not needed..
Apply heat stop in all runners, this greatly slows heat transfer into the heads and as a by product sends the hot gas to the turbo faster and hotter because it didn't bleed off heat to the head.
Coat chambers with the same thermal barrier used on piston tops also vastly slows the heat from migrating through the head.
While the head work isn't cheap, it is the # 1 area that can enable the user to use the power and not watch the temp gauge.
I have several customers that speak very highly about how cool there motor runs when pushing it, and a couple are pushing a lot of fuel just like I am and did with the build I posted several years ago, that motor would tow heavy all day and run cool doing it..