I am new to the site and excited to be on here! I bought a 1967 Firebird coupe that is a 400 4-speed custom interior with power windows. This car has always been my dream car since I was a teenager, and I finally took on the project of restoration of one. I have completely disassembled the car, with only the shell remaining.
My question for now is the axle, as I am confused as to why I do not have traction bar welded mounts on the axle. The traction bars were attached to the underside of the floor pan, all aspects of the underside were equally rusted, with mono leaf, original shocks, drum brakes.

I was able to decode the axle with the following information:

The stamp on the axle: PH 0620 G2
The number stamped on the Housing of axle: 3894859

The info stamped on the Pinion gear: 2 GM 3790627 11 39 4 67

I figured out it was 3.55 gears, and on my build sheet from the factory it shows 3.26 for car W/O Air and then over it says 3.55 under perf. axle.

Anyone who could help me figure out why the axle looks original as to when I took it off, but is missing the traction bar mounts that were welded to the axle?