Itinerant Air-Cooled

I'm needing to clear my rear drain lines for my sunroof.... ('74 bus). I'm wondering if there is access from behind the sunroof or if the only way to accomplish this is from the outside? Rear passenger side successfully cleared by running a pliable copper wire up that back but driver's side still clogged.

Front lines cleared but I fear driver's side is rusted through. Will deal with that shortly. (nice puddle behind the driver's seat after a nasty rain). Would this also puddle if the lines had been clogged?

I'm in Oregon, lots of rain and fir needles.... :) Thanks in advance.

look inside the rear engine vents. There should be tubes hanging down. unless your cat can clear it for you those vents are inaccessible to humans from the inside the shell. I put some extensions (or a long piece of PVC pipe) on my vacuum and used it to clean out the area between the inner and outer shell. You'll have to pull the sunroof to even vacuum back in there.

Thank you. So the rear drains are literally that basic, i.e., the water runs down towards the back of the bus and goes out the small drain holes... there is no additional tubing or channels, correct? I have blown/vacuumed between the sunroof.