you're right, the tsrm does show different part numbers throughout the years, but the 1986.5 part number is listed to work from 01/1986 - 08/1987, which tells me the 1987 one should fit. I have yet to replace them on my 86.5 though, only done my 89.
I would grab one from your local Napa and return it if it doesn't fit. The Napa one doesn't come with the bracket though, so you have to drill out the existing and bolt this one in it's place. Kind of good though cause there is a seal under the bracket which causes hatch leaks. It might even allow you to replace them without pulling the interior panels off if you keep the original bracket.
post back and let us know how it went! No doubt i'll have to replace them soon and i'll be pissed if I have to return mine to rockauto.