I am not sure but one thing worth looking at is the wiring loom from the sensor on the g/box on these,i think they run up to a big block connector on top of the g/box and from there up under the servo at the bulkhead,I would open up the loom at the bulkhead paying attention where the fixing straps are located and check for chaffing on the speedo/crank sensor wiring,good luck.
cdc
September 2014