72 has a LLB so most likely a 1971 if it is just LL... not that that really matters on a 2.73 open rear anyway... Jim J D Race
Troy, Here is your breakdown: 15-41 is a 2:73 ratio J 2 0 is your julian date,which is September 2nd 1970. Not sure if it is supposed to say LN,or if that is supposed to be another letter after the “L”. It was finished on the 274th day of the year.
Thank you Brian! This diff came with a posi and was marked 69 GS from yard almost 20 years ago. Just now looking at it again. It has tapered bearings instead of sealed. I'm going to put it in temp for my budget build, until I can afford Monza services. Thx
The late 69 rears have the tapered roller like the 70. Somewhere during 69 production,they changed the bearing style. So,if you have a 2:73 posi,then I think that code should read “LO”.
Brian, do not think that is Julian - Julian date code is just numbers, that is just factory alphanumeric date code that most manufactures of cast parts use . Troy - That other rear (1385724) is a 8.25 68-70 Buick only it has the 1.875 pinion and the 2 different size carrier bearing with the hard to get gears. and Fabcraft supplied gear sets 3.42 3.64. Pontiac in the mid 60's used a form of Julian date code 1-365 days of the year (like the axle tube in the troy example) the casting in some Pontiac 8.2 itself was only produced in one year (Nodular housings) so you would need to know the number of the casting and manufacture would say that number was build in 1969 only and then the 1-365 would give the day like 025 would be January 25th of (casting number of housing ) E.G. (220 ) <<<<< August 8th (Julian Type numerical perpetual per year) 9793020 <<<< cast only in 1969 so it is a 1969 august 8th rear casting. Firebird rear. Again more were done the standard Alphanumeric date code you have in your example. ( J 2 0 ) Which also some manufacturers did not use (the letter I) as 1 and I look the same on castings. Ford did this. Just more info trying to keep as much info up as possible for other to understand . refute if you need... JIm JD
Each brand had their different methods of making the julian date when it was cast,and another method of when it was finished. The J 2 0 translates to September 2nd,1970,and jives with the finish date stamped on the axle tube of 274,being the 274th day of the year,which would be later in September. Some brands,like the Oldsmobile rears,don’t use letters in their dates at all. The 71-72 8.5” 10-bolts are another. For example,the one in front of me was cast the 321st day of the year,and finished on the 344th day of the year.
Umm. Those pictures are from the same rear diff. I'm the first person to open it and drop the carrier out to check. It was marked 69 Buick from junk yard I got from. So...I dunno how it's a firebird with Buick internals 8.2. I know about the fabtech gears. I'm the one that supplied my dad's original gears that every 3.42 is copied from. I had to pay for 2 sets of gears they sent back, and they sent him a pile of disassembled crap that he has to reassemble, and buy all new parts for...So yeah, a lil bad feelings to getting fd over trying to help out. I have the original prototype gears, that I paid for. Monzas, I know it wasn't your fault. I appreciate you talking to me about this years ago. Anyway, should I be able to revert the axle bearing to the sealed style? How about the quick rundown on bearing parts list to go buy locally?
Troy, You might have the tapered roller bearing in that axle. If so,that is the common SET9 with the 712146 outboard seal. If you do have the obsolete sealed bearing,I have those in stock here.
Well I am thanking you now for your contribution and apologizing for the crappy send back of parts. I was suppose to get a pretty good discount on the ring and pinions too BUT that really did not happen for me either... So I do feel you for sure. Sorry for the headache. As for the Firebird thing...THAT WAS an example E.G. stands for (for Example) so I was only using the firebird rear I had on file for an example of Julian numerical code and casting number etc. Your rear is a Buick 724 casting 69 70 ish. You are good. All this was for a date code example that is all. Reverting bearing style. The only way you can change the axle bearing is to cut the axle housing tube end OFF and weld a different one on. Sorry. GS sealed bearing is RW507GR 68 - 69 STANDARD SKYLARK RW507CR 68 - 69 1970 LATE 69 SKYLARK OR GS IS A9 OR SET9 TIMKIN JIM MITSCHKE J D
Jim, as always, the Buick community family has always been straight up and caring . The discontent lay with ”outsiders”... But hey, a little pain for the benefit of others. Unfortunately, dad's diff has yet to be reassembled due to the pile of parts. I missed the Latin e.g. lol ..... Yes these are the tapered roller bearings. Thanks both Jim and Brian. Can I buy a bearing set from you guys, or is it just easier going local?
The SET9 axle bearings and 712146 seals are common,and can be bought at most stores,but it is the brand that you need to shop for. I use all Timken products. I can make you a kit,or you can source it elsewhere. Here is a complete bearing/seal list to rebuild the entire rearend: Inner pinion bearing = M804049 Inner pinion race = M804010 Outer pinion bearing = M86649 Outer pinion race = M86610 Pinion seal = 8620N LH carrier bearing & race = SET36 RH carrier bearing = LM501349 RH carrier race = LM501314 Axle bearings = SET9 (need 2) Axle seals = 712146 (need 2)
