I used an All Slots independent rotating axle & wheel set. The wheels are retained with small "o" rings that seat into a groove cut into the axle. The All lots axle was too short for this car. So using a MJK drill blank 3/32 axle ground a groove in the axle to take the 'O" ring . I did this on the Lathe with a Dremel with a cutting disc. the dremel was taped to a piece of tool stock & mounted in the tool block to enable fine engagement with the axle .
I tapered the end of the axle to assist the fitting of the "o" ring . There is a spacer on the axle at each end . So the axle can rotate in the tube as well as the wheels rotating on the axle individually. The Fly front tyres were fitted to the All Slots rims. The end of the bottom "A' Arm and the cut off king pin are trimmed to clear the front wheels . the A arm assembly will need few spots of glue to stop it pivoting
The chassis was set up on a block with spacing underneath to set it at the correct ride height & then screed to the set up block through the display box mount screw hole.
The front axle is squared with the rear axle & the set up block drilled each side of the front axle to insert some small nails to keep the alignment of the axle.
After checking the track measurement as shown and the both sides are the same the axle plate is lifted & epoxy glue (Araldite) is placed on the chassis where the plate fits
The plate is replaced , a large nut is placed on the plate to clear the body mounting boss & a "G" clamp is used to keep pressure on the plate while the glue sets overnight.
I changed the guide to a Sloting Plus wood guide which fitted well .
I fitted NSR oil lite bushes , A 26T Slot.it gear, and a 10 tooth MRRC plastic pinion.the mesh feels good!. I used MJK formula 1 wheels and the MJK Ninco F1 Tyres . The tyres fitted well and this combination is the same as an "Air Rim" effect as the rim is flat "cotton reel: where the tyre has a step recess.
The axle plate could be done differently if you are prepared to remove the driver support and some of the drivers legs .
Hopefully the car will perform well and at least the wheels should not fall off in service as the originals do. Also front & rear wheel alignment should now be constant .