Ok let's see how many folks can list their axle codes on their W30 cars equipped with AC

Edit: and build date of car and axle if known.

 

Here's mine November 18 1969 build. Car has AC (and cruise, among other options)

axle code SX W27

I'll try to see if I can find the date on the axle tube as well.

 

Sf

 

Yes,there is a julian date on the posi unit,so you can at least get an idea of when it was built,obviously after the posi unit was cast.
Is the ink stamp still on your cover anywhere?

 

I don't remember seeing an ink stamp anywhere on it, though I have never had it totally off the car. Is there a spot where it would normally be? I did see the SX code on it, was upside down if I remember correctly on the passenger side facing the front

 

The code should be on the passenger side axle tube.The codes were upside-down until 1970,when they began assembling the chassis right-side-up.Not exactly sure sure when that change was made.

 

My '70 W-30 w/ A/C:
Built 4th week of October, 1969.

SF rear end (3.23 posi)
Casting date on housing = 288 = October 15.
Assembly date stamped on boss on rear of housing = L16 = October 16.

Did they really machine and assemble the rear within 24 hours of casting it? Seems like it wouldn't even be fully cooled by then.

 

They assembled it with oven mitts.
I have seen the finish date,like your L16,stamped on the rear of the pumpkin,next to the cover,and on the cover itself,near the top.
I know I did one last winter,that was a January/70 rear,and the finish date was one or two days after the casting date.They are usually more like 10-14 days,or more.
I have also starting observing the Julian dates on cranks versus the blocks.Most of the time they are different,but I have two engines right now that the crank date matches the block date. Cool stuff.

 

Of course, there's also the possibility of the workers using the wrong date -- either choosing the wrong stamps/patterns or simply forgetting to change them until 3 hours into their shift.

My differential cover has an "M" inside a circle stamped near the "TOP" stamp. I assume this is not a date code and have no idea what it's for.

 

70 W-30 with A/C
SF 3.23
289 rear end date
L21 assemble date (5 Days after casted)
date on carrier is not very clear but i think it is 255
Ring gear date is 257
11B car build date

 

70 W-30 with A/C
SV 3.23 W-27
Rear end missing build date
carrier build date is 282
car build date is 10E

 

For the record,my buddy had a 70 W-30 A/C car that had the SF 3.23 posi rear. He has a copy of the window sticker and it has the 3.23 gear listed.