Top Plate for the Weight Stack.
See PN60600 for standard/non-functional trainer weight stack labels. Click "More Pictures" for weight stack labels chart.
More part numbers for your reference:
PN17080 Screw for guide rod top
PN16520 Black nylon spacer for guide rod
PN11340 Threaded guide rod insert
PN26130 Rubber finish washer
PN20660 "U" clip cable retainer
PN29190 Screw to top plate and shaft
PN60700 Top Plate
PN53600 Older selector pin for no 15LB plate stacks
PN20760 Older selector pin for 15LB plate stacks
PN60610 Current selector pin, used since 1/2005
PN46700 Selector shaft 15 plates
PN20630 Selector shaft 20 plates
PN69600 Selector shaft 25 plates
PN57670 under stack Bumper (need 2)