I don't understand the label but I see a 4-1-66 under tractor number. I'd think assy date would be titled differently, course on most it's just a one liner in the line of 3 lines consisting of model in code, assy date also in code, and serial number.
Edit: I & T manual #41 (just google it) covers my 3910, your 4910 and 2 others. My 3910 has an under the hood decal like yours that is unreadable and also on the FEL mounting "land" on the right rear of the engine are the 3 lines of information. The manual explains what is what on code meaning.
Edit #2: My tractor is a 1988. If 1966 is your year of mfgr, I didn't know anything over the 4000 basic series was available back then. But I didn't research the subject.
