Speedo gear chart vs. math...

percent works perfect as a correction, especially with automatics and TC slip. But I think you are gonna find that the closest you can get to perfect with some tires is about 2.5%.

3000/3.55s/25s does math out pretty close to 63, so you would need a correction of 40/63x 34= 21 teeth..... which is preposterous.
I would assume something is wrong with a) the tach, or B) the TC, or C) the speedo, or D) that 34tooth gear and it's install, or the 3.55s ain't 3.55s

Bottom line is; You are right to suspect that 2 teeth ain't right,lol..Good catch