Check the screw heads - if they have "hash marks" on top, they're SAE/Inch. If they've got numbers (like 8.8, 9.8, 10.9, &c.) they're ISO/Metric.
If they're ISO, and just about fell through the 3/8" threaded holes, then they're probably M8-1.25. The "9" you saw (should be 9.8 or 9.9) is the "ISO Property Class" - which indicates the strength of the screw (the numbers serve the same purpose as the hash marks on the SAE/inch screws - for SAE, add two to the number of marks you count, and that's the SAE strength/grade. Typical grades are SAE5 and SAE8.)
5-90