But the rear differential ..say was one.
What's the axle code?
3. REAR AXLE- (original) assembled January 20, 1969: All Z28 had 12 bolt rear ends.
12 bolt, 8.875”
Stamp codes on tube= BU 0120G1
E
Decodes as BU- originally a 3:73 gear (BV was a 4:10), with posi, 12 bolt for 1969.
01= January, 20= 20th day, G= Detroit Gear and Axle plant, 1= 1st shift, E= Eaton posi unit. BU was the normal rear end ratio recommended for the Z28. Doug Walker had the gears changed to 4:10 after he bought it.
Axle Housing casting(original) cast Jan 3, 1969: The photos of the housing show the following casted in numbers:
• Test numbers- 12345
• Test numbers- 67890
• Part # 3894860NF= 12 bolt casting #.
• GM58= GM Model number of differential
• CON1= casting foundry conveyor #.
• Date: A39= decoded as a= January. 3= 3rd day of month. 9= 1969 year cast.
Axle posi-traction unit (internal) is original but had new clutches in it.
Axle Gears (internal): Not original: The axle has 4:10 gears in it by manually counting turns. The clutches in the posi-unit were replaced in 1982 by a performance shop in Ankeny, and Laverty changed the axle gears from 3:73 to the current 4:10 in it now.