Topic: Differential Build Dates Question
in Forum: C3 Driveline Components
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Hello,
I have the casting number from the differential case and the stamped code for the gear ratio and assembly build for my 1969 Vette.
The casting on the case is B 24 9
The stamped code on the bottom of the cover is 1AZ 9 2 69
If I am assuming correctly the cast number refers to February 24, 1969 and the stamped code refers to late 1969 Heavy Duty 3:55 ratio September 2nd 1969 build.
Am I correct in my assumptions? If so, this further confirms the numbers matching aspect of the entire differential to the build date of the rest of the car.
Thanks In Advance For Any Replies!
Mike C
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Duncanville, TX - USA
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Looks right to me. HD 3:55 posi, 427, close enough build date for the car. 
The casting date is for the date the actual diff housing was cast, and the stamped alpha-numeric info is the date the diff was actually assembled.
|UPDATED|4/17/2017 7:18:23 PM (AZT)|/UPDATED|
The casting date is for the date the actual diff housing was cast, and the stamped alpha-numeric info is the date the diff was actually assembled.
|UPDATED|4/17/2017 7:18:23 PM (AZT)|/UPDATED|
Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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Overland Park, KS - USA
Joined: 7/9/2003
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Vette(s): 1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.
2023 Accelerate Yellow HTC Stingray
Was the HD diff and option or standard? First time I've heard of it.
1973 L-82 4 spd
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20218
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
HD diff had the bolt on, threaded style yokes for the halfshafts, instead of the u-bolt/nuts. All big blocks had the HD diff.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Limited Member
Send PM
Overland Park, KS - USA
Joined: 7/9/2003
Posts: 916
Vette(s): 1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.
2023 Accelerate Yellow HTC Stingray
Thanks. Never too old to learn.
1973 L-82 4 spd
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20218
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
This one?
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
As Adam mentioned the only difference is with the axle yokes. In all reality I have never seen a yoke break at that point. I have seen rebuilt axles break, twisted splines, worn axle faces but never a broken yoke. Many times customers want to upgrade to the "HD" axles but don't realize how expensive a used set of caps are, about $125-150 for used GM, which are the best.
Axle endplay is more important in my opinion. I set my diffs up for 005-007 endplay. You might want to shoot some cast blast on the cover bolts or they will rust up on you.
in Forum: C3 Driveline Components
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