O posted pics of the difference on the old site... I can post pics when I get home tonight....
Basically, the 87's are longer on the top mount of the spindle and the 88+ are shorter....
The Tie-rod bracket mount is also more rounded on the bottom while the 88+ is flatter if I remember correctly.... I can look for the pics tonight and post them....
I had the 87 spindles on w/ my stock 88+ arms and the camber was way off... that's how I learned that the 88+'s were different...