I have a 72 340 4-spd Demon im in the process of doing component restoration on. I just had the 8.75 741 case diff powder coated and im looking for all the factory inspection markings that would been applied as it came down the assembly line . My car has the 3.55 Sure grip in it. It was to rusty to get any good pictures before i had it taken apart for sand blasting. If any one has some good clear pictures of what im looking for would be a huge help, thanks Moparts great site.

I really doubt a 741 case would be your original unit. By 1972 you would have a 489 center, I'd check dates on that 741 to see.
Ron

Hi Ron i have 2 original broadcast sheets for my car on line # 4 the axle code is 183 does that mean anything to you ?. The diff looks 100% original to me .

Ron i also found code # D56 and # D83 on line 2 of the Broadcast sheet if that helps.

I found this online. Your car should have a 489 case

8-3/4"
1820657 (small pinion shaft, up to 1964)
2070741 (small pinion shaft, 1965 to about 1972)
2070742 (large pinion shaft, 1957 to 1968)
2881489 (tapered pinion shaft, 1969 to about 1974)

Yes, find the date code, but it still could have had a 741 case.

The D56 comes up as 3.55 69-74 so I would guess I've had this wrong in my head all these years. I always thought the 741 ended years earlier. I guess because you probably have a small yoke 7260 u-joint they used this unit in a-bodies still.

Sorry to steer you wrong.
Ron

Thanks Steve, Jim and Ron. Ive been told that the 741 case was still installed on a lot of cars well into 72 and i would have to agree. I had a 72 340 4-spd Duster years ago that was 100% original it also had a 741 case with a 3.55 SG i think 489s came a bit later.

I'm always thinking B-Body so that's why I screw up. Also I'm older than dirt. My 72 Satellite has the 489 center in it.
Ron

Two 1972 340 Duster and both have 741 case. Both 3.23 gears, four speed is a sure grip.neither one gives me a reason to suspect not original..