I am trying to install an AutoMeter transmission temp gauge. I decided to use the manifold that they supply to tie the temp sending unit into the metal line that takes the trans fluid to the cooler in the radiator. It is supposed to fit a 3/8” metal line, but is not quite right, close but no cigar. Maybe the line is metric? If anyone out there has a manual, does it tell what size this metal line is?

 

How about just measuring it? A couple metric combination wrenches will tell you quick and easy what size it is. Just start trying to slip the open end of various wrenches over the tube until you get the one that fits best. Simple. I'd be willing to bet it's either 8mm or 10mm. 10mm is just a shade larger than 3/8" and 8mm is about 5/16".