1971 chevelle rearend date

[wannaBBC]

I am looking at a 1971 chevelle malibu 400 with a ls3 bb ,4 speed , it is a # matching car ,,vin stamps are all correct my only concern is the 12 bolt rear housing is dated G 70 with august stampings and the car was assembled 12 /70, are these dates too far to be the original rearend, it doesn't look like the rearend has been out of the but you can never really tell forr sure, Thanks in advance for any info