Well, that;s not quite true Astrojet.
Ther is absolutely no way to visually distinguish an MD -81, -82, -83, or -88 from each other-unless it happens to be painted on the a/c. The differences are all internal.
Its the -87 that has the taller, pointed tail, and the fuselage is shorter. But it has the standard cylindar engines found on all other MD-80's.
The MD-90 has the tall pointed tail, and the huge, short engines.
The 717 looks like a baby MD-90, with the tall pointed tail, and fat engines, only it is much shorter.