Skippers, I am looking to replace my existing strainers (AC and Engine) with Groco strainers to accomodate the Aquaduk winterizing system that was recently purchased. I am not at my boat now, but need to know what the ID threads of the existing factory installed setup. This will determine whether I get the ARG-500, -700, -750, or -1000. Does anybody have the info I need? Thanks for any comments.