if your electrically inclined, and you have alot of time on your hands, you can simply swap the connectors etc from the 87 into the 91. The motors should work the same, and have the same colored wires. Just cut and splice. I did this with seats from a 89+ W126 and put them into my 83 300SD. I even rigged up toggle switches to get the power headrests to work.
96 integra SE....sold
99 a4 quattro....sold
2004 highlander limited....current.