Hi Gary
 I see this post is over a month old now, but I will try to help you if I can.  The 6-8111 Came with a "Select-able" Reverse lever.  I have an 8111 myself. It was a bit of a clunker when I picked it up. What I did was put a 2 position E-unit in it. I don't know what number it was, I just had one laying around from an old post war alco engine and soldered it in.  Might have been something like a #101-1. 2 position, short lever.  I just can't say exactly.  Before you start you might want to look for an exploded drawing of the 8111 and get all the part numbers you need. I think I had one around somewhere but not sure where it is anymore. As far as the nylon Gears, they are very prone to wear when put under heavy load. There are replacement gears for it.   It takes a bit of work to do, but if you like that part of it, then it's ok. You may need a wheel puller, not sure. You might find a whole motor truck for it somewhere too like on e-bay or Trainz.com. and change the whole thing out. The cost may be a bit much depending. I would run it for now with light loads and not pull heavy grades under load. Lubricate it according to the instructions. You might be able to find an entire working chassis and motor for it too. Swap the shell.  Brushes for the motor and all that can be found at Trainz.com or Ebay.