Hi Guys
Followed the instructions for modifying the gears to incorporate the extra clutch, This mod would be alot easier if done during building, but my trucks were alreay assembled, so a bit of fiddling and stripping down and I managed to do the mods to my second truck, I had to borrow a white clutch cog from another of my built sets, and some of the other parts like the L shaped beams are not included in the original 8258 set, so you will need to source these also.
Results are to be expected, no more crunching of gears and crane movements dont need to be closely supervised anymore.
A success!
Lego should provide revised instructions for future sets, or even an update leaflet to be inserted into existing instruction books,
Cheers
Ste
EDIT:
Seems I was a little hasty is calling this series of mods a success, The lifting power of the crane arm (lifting an object by use of upper or lower arm) is greatly reduced, this is because the newly installed clutches slip instead of allowing the arms to raise the object, if you prefer to use the manual winch to achieve this tho that works as normal.
pros and cons for everything it seems.