70 -72 Monte Carlo trunk lids will also fit your Chevelle.

Yes they are the same. Both the 71 and 72 rear bumpers are fitted wth round tail and backup lights. A 70 rear bumper will bolt on but it contains rectangular tail lights. The deck lids are also interchangeable from 1970 thru 1972 however there may be length difference between 2dr and 4dr models.