Yes I know, but this is the DI section, so I am assuming that he has a '99 DI.

 

Yes, a 99 DI, Will check out the VSS this Sat and let you know and will go to pull a part to get a new cover for the Crankshaft Position Sensor

 

Took me a while to find this topic again..

Thought this was a disco2.
The speed sensor on the tbox could go out of range while highway driving,
the ecm would see the vehicle over max speed,
the ecm cuts the engine off causing a bucking problem.
I've seen only 1disco 1 where that problem was actually in the ecm.
"Typically" if the crank sensor is bad, the vehicle won't run.
There were also problems with water ingress into the ecm..

My sincere apologies Spike.