So you are putting a engine that came from a 86 MT into an 87 AT. You are keeping the same engine harness that was in the car, in the car. Only the engine changes correct? The car was an AT and will stay an AT correct?
No problems, no modifications needed. You will need to fix your alternator wiring however.
[This message has been edited by phonedawgz (edited 10-21-2014).]