A question that crops up every now and then, so I've created this thread
"Brown Fingers" were fitted on very early C5's and were found to be too brittle, causing the fingers to snap when you attempted to remove the gearbox. There is also a suggestion that they simply snapped during normal use of the motor, but I cannot substantiate this. They were replaced with "white fingers" , constructed out of more flexible materials. The fact that they were replaced confirms there was a problem with the brown ones !
The "brown fingers" are shown in the photo on the left with the motor and gearbox joined .
On the right you can see the white fingers shown on the motor with the gearbox removed.
The colour of the gearbox is not a problem.
If your C5 has the brown fingers fitted it doesn't mean you shouldn't use it, but it is very likely the fingers will snap when dismantling for greasing. As Martin says, you can work around this by dismantling the motor first, and greasing the gearbox from behind whilst it is still attached to the fingers. A bit fiddly, but it can be done. Wizbat's C5 had the brown fingers which had snapped and were then "bodged" by a previous owner ...but that's a different story
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In theory, the brown fingers are most likely to be found on grey boot versions because these where the earliest models made. Although my first C5 was grey boot, it still had the white fingers - and boots are very easily changed. Physically checking the motor/gearbox is the only sure way of telling what is actually fitted.
Adam Harper still sells "white fingers", so don't be put off buying a c5 with the "wrong" ones fitted - it is a very cheap and easy fix
Hope this helps