Layne explained what the R means. A group number followed by the letter “R” means the terminals are reversed* when facing the battery with poles at rear of the battery from you, the Neg pole is on right.* If there is no R following the group number the negative terminal is on the left.
I learned about batteries when I had a big boat could have flown in a lot of cold beer for what I spent on batteries. In a nut shell they have so many amp hrs in them from new . If they discharge more than 25% their life is reduced so you want to keep them above 75% for best life That’s their sweet spot .
Discharge them more and suffer accelerated battery degradation
If I get 7 years out of a battery I’m happy it’s hard on alternators running weak battery’s
I’ve load tested battery’s
Used a hydrometer
Ready to go all good
Come to use the car a month later …dead …
Batteries seem to last 3-11 years luck of the draw Ymmv