Contrologix Power Supply

Need to buy some contrologix power Supplies and looking at the spec info i need a 1756-PA72 or a 1756-PA75. In the specs i don't see a lot of difference in the 2. I will be giving it a 120 VAC supply.

The 1756-PA72 says series A and B and the 1756-PA75 only saya seres B. Does this mean the series of the chasis?

Is the 1756-PA72 still produced?

I was looking at specs here http://www.ab.com/en/epub/catalogs/12762/2181376/2416247/360807/1837526/print.html

For one the current ratings are different:

PA72 5.1V @ 10A, PA75 5.1V @ 13A