IBM Thinkpad T40 Hardware Maintenance Manual page 105

Removing and replacing a FRU
Cisco Aironet Wireless 802.11b
In case of the antenna jacks have the tabs, plug the gray
antenna cable with the tab marked MAIN into jack M, and
the black antenna cable with the tab marked AUX into jack
A.
In case of the antenna jacks do not have the tabs, plug the
gray cable to jack M, and the black cable to jack A.
MAIN AUX
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ThinkPad T40/T40p, T41/T41p, T42/T42p Series