Anyone know why Chrysler reinforced the 74 Challenger roof?

[Challenger6pak]

I am parting my 74 to use as parts for my 70 R/T and my 73 Rallye.  I noticed the roof and pillars are reinforced.  Was this due to the belt attachment or just a government regulation.  I'm just curious.  Thanks,
Tod

[Challenger6pak]

A-pillar

[360 'CUDA]

Probably to give the porthole window extra strength...       J/K

I noticed that reinforcement also.   I'm sure your right about the seatbelts and gov regulations.   I don't know if '74s are all that much stiffer driving around but maybe they are better in a rollover situation   

[74MOPAR]

 I beleieve the seat belt attachment point would have been just the same.
Probably for rollover legislation that never happened. that is why GM changed the Chevelle, Cutlass, etc. to the "collonade" style roof in 1973, rollover protection that never was passed by the gov't but it was seriously considered.