can i only run a upper and lower rad hose? if i not running a heater core?

 

Yes you can. But there could be a couple of simple things to keep an eye on.

If you have a plastic radiator tank with a molded plastic nipple where the heater hose returned, then you'll have to cap the plastic nipple with a rubber cap and a clamp. But be aware, those rubber caps can't handle the pressure for months-on-end, and they'll eventually split and blow. So keep an eye on it, keep spares onhand(and in the car), and change it periodically.

Then if you have a TPI engine, you've probably performed the "Throttle Body Bypass," removing the coolant flow from the throttle body. And now by removing the heater core from the equation, you'll probably be removing the "U" hose that runs from the front of the intake manifold up to the throttle body.

So here, again, you'll have to use a rubber cap and clamp on that nipple. And, again, keep an eye on the cap here, too, because it won't last either.

But with the intake manifold nipple, there's another, more-recommended option. Instead of capping it, you can completely remove the nipple and plug the manifold, leaving you with no worries about cap failure.

 

I just routed the flow to the bypass to the heater hose return. no plugs.