Just looked in my manuals. A 1977 Cessna 150 has the 10 year life according to the service manual (page2-27 date 7 OCT 2002), the same part number harness is listed in the 152 IPC, but the 152 service manual has no life limit.
Glad the harness knows what aircraft its fitted too, maybe that explains the cost!
However, all 3 of my current 177 manuals (68-78FG, 71-75RG and 76-78RG) have the 10 year life for the harness.