I finally got around to fixing up my 92 sc400. I installed brand new lower control arms, changed transmission and differential fluid, pads and rotors all around , and got 4 brand new tires. The cars always had a bit of a shake on the highway and after all of this it’s still there. I believe the shaking to be coming from the transmission.The shifter shakes back-and-forth and when I grip it with my hand I can feel it shaking beneath. Praying it’s just the transmission mount and not the transmission going out. Before I buy a new mount has anyone had this experience before? Other threads mention transmission mounts but I haven’t seen one that discusses it directly. Thanks!

 

Trans mount and alignment.

 

Check your drive shaft and rubber couplers.