+1 on the diff over the spool. I have a box stock ta03 diff in my M05 now and it was very smooth to drive last night.
Spool was just too savage on tyres and always felt like it was running on the ragged edge of disaster.
I'm running the stock tamiya plastic front blocks, rear uprights and steering rack.
This is on the short wheelbase too.
My next moves are to add extra shims to the thrust bearing and add a little more toe out for turn in.
All in all,I'm finally happy with the car and having a ball with it.
Fleety.