Posting for my dad. He has a 2002 ranger 4cylinder, 2wd basic truck. Leaking out the transmission dipstick tube. Is the only thing sealing it an oring? The end of the tube has a flange that keeps it from going into the transmission any further. No oring was on it when it was pulled out. Every dipstick tube ive found has a grooved section with oring where this tube doesnt, just smooth until it gets to that flange/lip.

Thanks to anyone in advance.