Cant speak on behalf of spectra but I used a murray heater core. no issues at all plus lifetime warranty. Also have a murray radiator in my bronco.
I agree with above, just because the hoses feel (hot) doesnt say anything. Make sure are for sure getting up to temp. Also dont know on the slant six but is it possible to mix the two hoses up with one another?
http://m.oreillyauto.com/h5/r/oap/s...=Search_02709_5137346_2191&pt=02709&ppt=C0331
