I had similar issue with my new 3.6 the other day, but I thought mine came from the back.
It was low speed low RPM and it rattles as long as the pedal is pressed.…
Thanks for sharing, OP. I'm looking to achieve the same sunrider + pioneer platform results
From your experience, would you say that a 60 x 56 platform would fit the backbone mounts? It would be as if you cut another 6 1/2 on other end of your rack...