I am looking at William Wonder's excellent book Thunderbird Restoration Guide 1958-66.
For both 58s and 59s there is a section on Transmission I.D.s (pages 28 and 46).
I believe the first number is for the year, so 1958 (8). The second character is for the month (N) and the last two are for the day (17). in your case.
The tough part is the N. He lists January through December as being represented by A- M (I is not used).
So my guess would be that yours translates to January 17 of 1959 at the tail end of the 1958 tranmission run. But that is truly a guess on my part and someone else might jump in here and set things straight or email an authority (which I ain't). A man named Alan Tast is perhaps the real expert on such matters.
The good news is that it precedes the date of manufacture for your car, leaving open the hope that it is the original tranny.
Is it a Cruis-O-Matic?
What was the date of manufacture of your entire car??
Last edited by JohnG : 08-08-2007 at 11:03 AM.