I think I started a thread about this but I believe that yes there is a difference. I bought one from a forum member that will not properly fit in an 84. It curls up around the bulkhead and rollbar.
I have another mat in another 84--My never going to finish red SL--that the mat fits perfect in. However, the red SL has no bulkhead yet but everything else fits great.
I haven't had the time to compare the two like the picture above. Always willing to trade for the correct one.