Don't worry about the reflash.........
... ... ... . unless I missed something (and I am not on here as much as I used to be, so I could have missed it) only the 98. 5-99s need the 18-11-99 reflash. At the time I did mine, there were two reflashes, one for the 98. 5s that was the infamous emissions reflash (DISASTER), and the one I referred to, 18-11-99..... which made big diff for me personally.
As a kinda humorous (but serious) side note: Some poor fellas on this site have gone in to their dealer asking for the reflash, without specifying which one to get... ... and got stuck with the emissions related one--which turned the rigs into gutless fuel hogs... ... and in the case of a good pal of mine, he took his in for minor warranty work (his is a 2000!) and they stuck in a "reflash" and didn't tell him!!! MPG went into the toilet, as did the power..... he couldn't figure it out... ... . and went to Cummins. Shop mgr came back after a few minutes with a slight grin on his face... ..... the dealer had stuck the emissions flash into his 2000! Cummins reflashed it with what was supposed to be in there... . NO CHARGE. Said "Thanks for coming to us, let us change yer fuel filter or whatever else you need sometime..... call it even". Now THAT'S customer service.