rubber transmission lines?

[71GMCinTN]

Anyone use rubber lines (high temp/high pressure/etc.) instead of metal for their trans lines? On this truck, they had lines run to the cooler only from the trans. (figured it was a manual trans. radiator before I looked) They had used uncut lines, and stuck the flares into the rubber cooler lines and clamped them.
Still had old trans. lines hooked up to the radiator, that were cut about 1/2 way, so I figured it must be something wrong with the radiator, but I hooked up an air line to one line, and it held pressure fine (no air bubbles in the coolant).
My first thought was to have the right fittings (2 for the trans. 2 for the radiator) and just use rubber hose instead of metal lines so I could run them away from the headers. Have read that it's better to use as little rubber line as possible, and will be a prob. eventually. Plan to reuse the cooler, and will have rubber lines on it.