Parts for rebuilding the 4-speed are available, and it's easy to work on. You don't need to convert to 12 volt, as long as the grounds are good, and the positive battery cable are the correct guage, 6 volt works great. As Rich said, the mirrors and rear bumper are not original. The tire size would depend on what size rims - 15" or 16". It is very possible that the shifting from side to side is due to worn out front end parts - tie rod ends, king pins, etc. The front end can be tightened up relatively easily. I hope this helps. There is a lot of information here, for what ever tasks you need to accomplish. Use the "Search" button, and ask.
Samantha
