Good point. I have thought about going this direction too. Does capping the trans lines eliminate water from leaking to the ground? I am not completely clear on this.If the only all-metal radiator that fits doesn't have a transmission cooler, exactly what problem is being solved by using it? As far as I've ever heard, the stock Toyota radiator is pretty darned good except some people believe when it gets old it sometimes allows coolant into the transmission cooler. So, why not cap off the stock transmission line fittings and use an external cooler instead of buying a new radiator that will likewise require an external cooler?
Ultimately, I want an all aluminium radiator that is high quality and that has a trans cooler built in that is extremely reliable. What I really want is a high quality racing radiator, and I am willing to convert to electric fan if necessary to fit it. I am just hoping that someone has done this already and can provide all the info needed. I think this forum is in desperate need of a "how to" on this.