If I am thinking right the ntk spur is standard 1/8scale 24 pitch/metric, same as the ofna. My guess would be other spurs could even work from the XTM kits and others too. I made bearing spacers for the torson race diff to fit in the ntk case but if I remember right, boca had the right size bearings when I checked. It's not a hard mod to me but it does need a few mods obously since it's for a Kyosho. If I ever get back in the mood I will take the torson back out of the truck and take more pics. I think just about any reg diff might work as long as the housing case is 24mm? or smaller. I put some info in the posts so hopefully that will help with your questions. I think I got a few more things saved somewere that I will post later.
To me one of the most important mods is/was when I started to setup a front brake system, having front brakes would be a super big deal when going up against the better1/8scale buggys on the track, I could run on par on the straights with them if not overtake them, the problem I was having is they could overtake me in the corners because I had to slow down more before hand because most times I was carrying more top end speed than most 8scale bugs. So anyway this is the mod that most interests me if I start messing around with this stuff again.
With the exception of a few odd parts, the guys here have not really tryed or had the need to change out a whole lot of the stock components on these kits because we don't really have any real big failers of the stock parts/components, more of a bigger issue is better setup then the way they came out of the box. I have always just ordered the factory stuff direct from mrc in the past in bulk (because I am/was a dealer for MRC) for me and the local guys here so most of us got lots of parts, but it is very neat to see guys trying diffrent things on there kits like diffrent suspensions. In the past me an an X POS pretend friend were trying to buy out the tooling/rights and all parts for this kit and we were trying to make a deal with MRC but I kind of droped out of it all and got busy with a divorce lol
which I am finaly finishing up so I am not much into or around the r/c stuff much anymore and was not much into using fricken computers at all lol. I have to be honest and say this was a nice change for me to come back and post some stuff again. I took in the factory world super8scale promo vid to get it put on cd rom so I hope I can post the orignal promo sometime next week.