[joeydurango]

I replaced my stock radiator with a Summit-sourced one that was supposed to be factory correct. It looked the part, and I guess it was factory-fitting correct too, because the factory transmission lines threaded in perfectly and have never leaked. As I recall, they were brass with a tapered seat, similar to what you have in your photos. No experience with the "straight thread, no cone, o-ring" setup you're apparently needing.

If the guys who made/sold you the radiator can't tell you what to get and where to get it, maybe they should receive their radiator back. That seems like a major breakdown in basic customer service to me.

EDIT: You posted the same time as me. Well, okay, that guy was a reseller. He should still know this, or be able to find out. Or, you could call the manufacturer direct.

I think you're on the money with the description - 1/2" x 20 is very straightforward, straight thread sounds to me like they're specifically saying no NPT fittings, and I have no idea on the G1/4. Never seen that before.