Hard to make out the yellow stamp date on the diff, maybe 9-18 ?
There may be another such stamped date on the left axle tube, clean that area carefully. Should be a later assy date than the diff.
What's the SPD (scheduled production date) on the fender tag ?
Any upper engine block pad stamps ?
As for the car itself: a '68-'69 will have J in VIN (5th position) and rosette VIN tag rivets.
Also K-frame sump guard, reinforcement plate on floor for pinion snubber, rear spring mount gussets & plates.
Hemi-specific underhood harness.
Oil pan bolt in pic is non-factory, FWIW.

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