Nice work. Perosnally I have abandoned using the mato lowers for Taigen after having two matos.
If you have gear box issues, it will likely be the pinion spinning free on the motor shaft. And the set screw in the pinions was rammed tight in the pinion but didnt come out the inside to contact the shaft. The shaft is knurled and the ponion was just rammed on the shaft.
Purchasing new pinions and making a flat spot on the motor shaft was required. I also upgraded motors. The tamiya ones that Danville sells are excellent once you hack off the brass pinion for the frog kit.
Also, the coil srpings on the mato lower bogies are doubled up due to the intedned weight of the metal hull and turret. If you pull the springs out and seperate them and replace one on each arm it rides so much better.
oh Also, keep your axles oiled alot. The metal wheels ride on metal axels. No bushings or bearings. I have seen mine gual up and bind tight a few times and I keep them oiled.
So dissapointed with Mato.
Any way, great work with the M4 hybrid. Love that look.