rear end swap help?

pakerz27 said
1973 was first year all Darts got the 8.25 rear end

Yes starting in 73, the a body could get an 8.25 rear if order. A sbp/BBP 7.25 rear was also an option if a slant 6 or front drum brakes were ordered.
The 8.25 was the replacement for the 8.75 rear.