[apokatastasis]

In 1980, St Petersburg's Skyway Bridge was rammed and badly damaged by a freighter. A number of vehicles fell off the bridge, and "of the victims who made the fall there was only one survivor, whose truck had luckily landed on the deck" of the freighter.

Perhaps this is what "Skyway bridge-18 wheels" refers to?

"Oklahoma-Ryder Truck" - I assumed that was about John Doe #2 (and therefore ambiguous, since some people think he was an agent of the state, others a foreign collaborator).

My feeling is that the person who sent this letter thought that 9/11 was an inside job, and the moment that anthrax hit the news (October 4), they assumed it was more of the same. "Blow away this dust so you can see how the real thing flys"... I hate to admit it, but it does sound like a reference to the aerosol properties of the real anthrax, doesn't it? My head hurts!

[apokatastasis]

Okay, I think I get it now. "Oklahoma-Ryder Truck! Skyway bridge-18 wheels." It's a threat to blow up an 18-wheel truck on the Skyway bridge in Troxler's hometown of St Petersburg. Not so cryptic then - just another threat.

The letter to Judith Miller reportedly threatened an attack on the Sears Tower. I can't find the text of it anywhere.