If you can't see the tail or the stab, I've found luck with the fleet number on the gear doors. I've seen it be drastically different from the actual tail number, though I can't remember which airline; it might have been Delta with some of Northwest's old Republic-sourced DC-9s.

If you can't see the registration number because of the gate configuration, there's also usually a Fleet Number somewhere that's visible near the nose of the plane (Landing gear door, sometimes under or over the cockpit glass).

If you've ever spent months building a spiteful LeMons car (no matter how glorious), you can't help but have that reaction the first time it actually works.

Well, this made my day (the diesel Porsche and this poor fellow needing to see a Burn Unit now).

Because working on cars is difficult?