So I noticed on my new truck the trans lines are looped and not plugged on to rad cooler. Just 2 metal lines with a piece of rubber hose and clamps tying them together. I was gonna just reattach them when I noticed the darn fittings are slid back on the rusty lines and and have now rusted in place. I don't want to replace the lines. Could I just put new fittings on the cooler with short stubby lines approx 2 inches then use rad hose to join the stubs with the original lines. What do you think?

 

First question is why we're they removed to begin with? Is the tranny cooler leaking into the radiator? Might be a better option to run an auxiliary cooler instead.

 

Agree there is some reason the originals are not connected. Fittings buggered up? leak? Also agree a cooler in front of the radiator is a good fix. Your transmission will thank you. Get a big one and no other cooler is required. Connection to the added cooler is typically by rubber line so you can just take off the rubber "jumper" and hiook it up.

Not really necessary but some penetrating oil and gentle heat + time may loosen up the rusted tube nuts.

 

I replaced the rad so I'm confident. That it should be the problem

 

I don't really understand what you're asking, but inverted flare nuts need to thread into flare fittings. If rubber hose must connect to a metal line, the metal line must be barbed. These lines are probably 5/16 inch. You won't find radiator hose that small. If you want to use rubber hose here, use transmission cooler hose which is sold in 5/16 inch.

Make this a lot simpler and just replace the lines. Transmission cooler lines are reproduced for a lot of common applications. Check with Inline Tube. If they don't have your original set already in stock, they can custom duplicate your original lines. I've used this service multiple times.