Finally received the rest of the parts and now have it pretty much all assembled.
The I2C level shifter and the rest of the parts arrived and I have assembled everything and seem to have everything working, most of the time...
The HC-SR04 ultrasonic sensor is installed along with the Arduino NewPing library. The I2C level shifter took some soldering, which I haven't done in a long time, but I think it's installed OK. I also installed the second dual H-bridge for the front motors and I installed an Arduino Sensor Shield to give me more access to the digital and analog
