So long story short, I did a TII swap into a vert and reused the stock radiator from the vert. It had the nipple to the overflow tank on the radiator and the blocked off plastic piece on the filler neck above the thermostat, so I swapped the plastic pieces around and used the blocked off one of the radiator and put the purge above the thermostat housing. The stock radiator ended up breaking and I got a Koyo to replace it with. The Koyo for the S4 has the nipple to the overflow tank on it, so now I have two nipples that need to go to the overflow tank.

Should I use the one on the Koyo and block off the one above the thermostat, or hook them both up? FSM shows the overflow hooked up to the radiator, and no tubes coming out of the filler neck above the thermostat. I thought the overflow had to come out from the highest point for some reason, am I wrong?

For reference, car is an 88 vert with an 87 TII engine. Koyo is for the S4.

 

just use the radiator line, it's not wise to use one on the thermostat housing because they break due to the weight of the hose, heat and vibrations.