After getting the body into a state that is OK with me, I decided to do the RC4WD hex conversion. The front was straight forward and easy. I can't however say so for the rear. The issue that caused me most trouble was that the rear shafts fit very tightly into the differential gears. To get the differential gears onto the shafts, I ended up using a vice.
When I used the vice, I ended up getting the differential gears too far onto the axles, so I had to get them back out a little more. To do this I had to take the rear axle apart and even take the differential apart. This meant that I couldn't follow the assembly instructions from TAMIYA as parts had to go together in a different order when the differential gears are attached to the shafts.
The reason to do a hex conversion is to be able to use different wheels and tires. Right now I have put on a set of Pro line 1.9 XL Super Swampers. These are mounted on a set of G-made VR-01 wheels. In the centre I have put on a set of G-made wheel hubs. The bolts in the wheels have been replaced with some stainless steel hex head bolts whereas the nuts are the original ones that came with the wheels.
The RC4WD hex conversion doesn't fix the wheel offset problem. I do have some ideas on what to do about it. Currently my intention is to widen the track width at front so I won't need to modify the original parts.
Some pictures with the new wheels: