with either design, what do you guys do with the gasket? i've assembled one from the ace hardware parts version and tried it in my van with disastrous results - mainly because of the cap design. it was a twist lock type cap and it leaked the fluid right away. i wound up doing the pump and peek cha-cha. for those types of reservoirs i think maybe a rubber stopper would work. i'm still waiting for my MB cap to come in - pep boys was out of the GM one...