Weird Driveline VIBRATION? (Suzuki XL-7 4x4)

The 2002 Suzuki XL-7 4x4 PHAD shop truck has been developing an annoying vibration on the highway, driving in 5th gear under load. It has 180k miles on the odometer. I take a logical approach and attempt an affordable DIY repair, to take care of the problem before something big is damaged. TESLONG NTS 500 ENDOSCOPE: https://www.amazon.com/dp/B07SQ4FLYX/?ref=exp_pinehollowautodiagnostics_dp_vv_d LISLE 49200 SNAP RING PLIERS: https://www.amazon.com/dp/B0009OR8ZM/?ref=exp_pinehollowautodiagnostics_dp_vv_d Enjoy! Ivan