340 water neck leak.

gentleman

ive had enough chasing a small water leak at the thermostat neck on my 340. the surfaces have been cleaned and scothbrited lightly down to bare metal and new gaskets and light rtv sealant used twice but still seeps lightly. the intake manifold is new performer rpm but the neck is the original. im thinking on replacing the neck. i heard the chrome ones dont seal well but is this just a myth? anyone have chrome that is not a problem? dont want to waste the money and still have no seal. ive also seen the chrome with o-ring type on e-bay. are these any good? just trying to do my homework before i buy. thanks.