I believe they pertain to date of manufacture, which is calculated in days from January 1st, and the 2 letter code would be for vehicle application.:TU: Someone please correct me if I should ever be wrong though.:grin:
You are correct Tom, The tag identifies: Mfg. code for model usage, Year, Engine or Vehicle Usage, Production date, also, Year, Usage and Trans. Production Number. :TU:
I'm from the Land of Olds, not Buick, so you guys can tell me I'm full of it if you like. I'd rather learn than teach. TH-400 tags are stamped with a sequence of characters similar to: 70 - OW - xxxx where: 70 = model year. OW = application code, an Olds W-30 here (which was also used by some Buicks, if I'm not mistaken). xxxx = sequential number. Started with 1001 (I believe) and could be 5 digits, depending on how many of this model were made that year. I have found no evidence that those last digits encode a date in any form. I have found significant documentation (in the Land of Olds) that those digits are a simple, sequential serial number. However, it appears to me that, once manufactured, those transmissions were warehoused and could be installed in any order on the line. So there's no guarantee that an October car will have a tranny serial number lower than a November car. I have found a casting date code on my transmission's tailshaft housing, but not on the case itself. The one on the tailshaft has a "69" in a center circle, surrounded by 12 pieces of pie, with dots in 10 of those pieces, meaning it was cast in October of 1969. Comments? Others' experiences?
Brian, My 71 BB Stage-1 trans has the sequential and a 3 digit Julian date as well. It is just to the right of the rivet. Double check yours. I bet it is there.
One other point: The Julian date corresponds with the component manufacture date and the VIN number stamped into the "pan rail" ties each tranny forever to the car it's installed in.
Nope. I've seen numerous Olds TH-400 tags stamped similar to mine. Maybe tags for Buicks were stamped differently, with both sequence and date? Seems odd for parts coming off the same HydraMatic assembly line. The tag on my W-30, as best as I can type the stamped part, looks like this: 70_-_OW_-_____233_8 I've put underscores above where spaces are. The last four digits are right-justified, meaning there is a large gap between the dash and the 2. There is a small gap between the 3 and 8, for what it's worth. I've seen other Olds tags right-justified like this, too. Is that big gap where the Julian date code is stamped on yours? I guess it is possible that my trans is serial number 8, built on August 22 (233). But not every tag I've seen (which admittedly isn't many) has that small gap. Anyone else got comments? Does Duane want to weigh in?
No Duane does not want to weigh in.:laugh: Most of the trans tags I have seen have both a sequential number and a production code stamped into the tag. The sequential number lets you know how many units were assembled since the beginning of the model year. As stated many times in the past I will not discuss production numbers. However the above info ONLY lets you know when the trans was assembled. If you want to know when the trans cases were made you need to look at the date codes that are cast into the cases, and they did have them on both Buick and Olds transmissions. If you guys bought one of my Date Code books you could easily figure out the date codes. They even have pictures of each style code, so you know what you are looking for.:Smarty: Duane
If you guys bought one of my Date Code books you could easily figure out the date codes. They even have pictures of each style code, so you know what you are looking for. Duane Come on guys buy a book their excellent....... Does this qualify for a commision....:Brow:
I found my clock codes thanks to Duanes book. Funny my case was made in August 70 and trans assembled not until late December of 70.....Black Gold; Did you know the Olds OW trans was used in early production 71 Stage-1's as well? They changed over sometime mid year back to the BB. This was do to the transmissions coming out of Different plants as there was a strike or fire or something in the Buick supplied plant. Apparently the OW and BB were essentially the same transmission.
Yup, I knew some Buicks used the OW trans. That's how I justified jumping in here with my Olds hi-jack. I have Duane's most-excellent Date Code Book and have recommended it to many people. My mistake was in posting without having the book in front of me. I looked at it last night and now see what copperheadgs1 is talking about. In Duane's example, I see the Julian date code 233 just right of, and above, the rivet. OK, that's something new to me. The TH-400 tags with which I'm familiar do not have that entire "field" of characters (painted and stamped) above the rivet! They just have the big "O" and "W" painted in the upper corners, and the line of stamped characters below the rivet. I take it from your comment that there was more than one HydraMatic assembly plant? Maybe the different plants used different tags. Or maybe Buick required HydraMatic to use a different tag than Olds did. I hope I haven't confused the issue too much, and that Ken got his question answered. I'd appreciate hearing of anyone else's experience regarding date codes being stamped -- or not -- on TH-400 tags. This topic is near and dear to my heart, because my W-30's OW trans is missing it's VIN stamp, but I have other indications it is original. [Duane, for what it's worth, in the text below the TH-400 tag picture you make no mention that the 233 is a date code. This is in contrast to the rest of the book where you clearly explain each date code. You might consider addressing this in your next edition -- for dummies like me who can't figure it out themselves.] ou:
Brian states, "[Duane, for what it's worth, in the text below the TH-400 tag picture you make no mention that the 233 is a date code. This is in contrast to the rest of the book where you clearly explain each date code. You might consider addressing this in your next edition -- for dummies like me who can't figure it out themselves.]" Brian, Well to be bluntly honest you are a dummy, but I do mean that in a good way.:laugh: The example in my book, of the OW trans with the "233" code is not a Julian date. If it had been a Julian date then I would have explained what it was and how to decode it. (I have examples of trans tags with numbers of 367 and greater, so if a year only has 365 days then how could this code be a Julian date?) The only real "date code" on the tag is the last 2 digits of the model year, and I called that out. This particular code is the transmission production code, and again as I have stated many times in the past, I will not discuss either engine or transmission production codes. My book was designed to help people decode the various parts on their cars, so they could figure out original vs replacement parts, however the intent was not to give anyone the ability to fake a car, therefore I refuse to discuss production codes. By using the trans case Casting dates, and the various other date codes on the case/tailshaft/side cover(for manual transmissions)/tags, etc, plus the partial vin numbers stamped into the case, you should be able to determine if the trans is indeed correct for your car. That is what my book is all about. Just because something looks like a duck, walks like a duck, smells like a duck, and tastes like a duck, does not mean it's a duck. In this case what people think is a Julian date, is actually a production code. Now, without going into any detail I will say this much, production codes do increase as the production year goes on, therefore if you take the time to track the codes for any particular year/ model type, you can get a good "estimation" as to wether a particular part falls into the correct time period, BUT, that's all I will say, and this is exactly why I did not want to "weigh into" this discussion. Duane PS. In this instance I believe my book will stay as written.
Gotcha! :TU: Now I understand. I was confused by those who posted previously and called it a Julian date, and I was not understanding the significance of what you call a production code. Thanks for your help!
There goes that theory out the window. My code just happens to be close to what a correct date code would be for my car. Now I ma curious on OW trans. I will have to crawl under my freinds 72 w-30.
Dave, Don't feel bad I've had lots of theories go out the window, but thankfully after 20+ years of research and cross referencing thousands of cars I think I figured just about everything out. Here is a pic of the "OW" tag, enjoy. Duane
Deciphering date and other codes is sometimes like reading tea leaves. You see what you want to see. Here's a picture of a 1970 Olds W-30 OW tag. I've obscured several digits, because it's not my tag and not my picture. Note how it's missing that entire field above the rivet, as compared to the other pictures posted.
Not to stir the pot guys but I have also seen different color tags for the same tranny's. ie: 71" BB in gold (yellow) color and some blueish or green ones !!!
Different colors for different years. I would bet the black one Black Gold Shows Is an older unit. Duanes I would guess is from a Buick in 71. Interesting comparisons.
I answered my own question. I see 70 on the Odls now. I wished I had paid more attention to my 70 W-30 when I had it.
