The experts have come back, 39 on the crownwheel and 10 on the pinion makes it a 3.9 diff ratio and I need to find an Estelle 120 5 speed to get a 4.22 diff. This will lower the top speed, which is no problem in a trials car, and lower all the gear ratios making it possible to climb the hills with my 58 bhp.

I've also now got detailed instructions on how to raise the suspension, which requires some machining and engineering. I have entered the Exeter trial in Class 0, so we don't need to get the work done until after that. I am looking for a gearbox and engineering facilities, will probably end up in the workshop at Cornermotorsports borrowing Andy's ramp and Skoda expertise.