As rusted as a few of mine are I never had to change the transmission lines. I did have to replace the power steering lines in one and the nipple on the power steering high pressure line. But that was it.
Those 2 Transmission lines run straight back to the transmission on the passenger side. Those should be fairly easy to do provided they come apart at the unions. They are not super high pressure as they are just the coolant lines to cool down your fluid.
I would soak the connections and all the bolts with really good penetrating oil for a few days or a week prior to changing them.
I use Kimball midwest pentratrating oil. However, JB blaster, Wd-40 etc will work.
Are they leaking really bad or starting to seep?
If leaking, make sure you keep your transmission fluid level up with dexron fluid as you do not want to run your transmission low or out of fluid.
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