I've been wondering how to do that on my 3950 which is similar to the 3600 in that area. The only thing I can think of is through the pocket door (with door removed). Maybe?
I just got it done. It was easy. I accessed it through the access cap under the faucet. I would recommend taking out the screws that holds the flange that the cap screws into, they are very sharp and the hole is tight.
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2017 Ram DRW 4x4
2012 Voltage 3600
2015 Road King, 2010 Tri Glide, 2002 Heritage