Those upper arms are still plentiful. We are all hoarding them cuz we're not ready to toss 'em out yet.
But in a pinch you can tack-weld the new BJs in; just don't cook the teflon seats out of the good ones. Four tacks about 3/8'long, at the corners,has worked for me. Make sure the weld penetrates. That will give you a few more years out of those arms, and a few years to find good ones.
