The fordo in my '58 custom 300 is leaking where the dipstick attaches to the side of the pan. I tried installing an o-ring, Teflon tape and even RTV. The manual just says to tighten it up if It's leaking. I've used a cheater bar to tighten and it still leaks. Any suggestions???

58 Ford Custom 300 - San Pedro, CA (So-Cal)