Inner CV joints (the one with the Gearbox) are designed to provide a mechanical play of about 02 inches to the Axle Shafts. Car during operation moves in and out of the bumps hence causing a different Displacement between Gear box and Wheel Hub, e.g When the car goes down in the bump, the shaft needs to stretch, The inner CV joints also called Star joints provide that.
Over the time the grease in the Inners gets dry and the Polish is worn off. The cars diff starts slipping hence causing vibrations during accelerations and also increase the gas consumption.
Specially cars with bigger engines who have a strong backlash are inherent to this issue. e.g an Xli wont do that even at 100,000km but an ALtis 1.8 will start doing it at 100,000km.
Get a Kabli set if in Pk, use Fingers to feel the inner polish. If its worn out dont buy.
Maybe this helps