Rockauto order ? rotors, size?

Hey guys I have a question. I took some disc brakes off of a 73 duster for my 67 dart and am ready to re-assemble the front end.
I am looking at the rotors on rock auto.com they show this--below

do you think this is the only size and if not how do I measure the rotor to make sure I get it right?
These are approx $53.00 each and why do they not show a left? any ideas?

what parts should I be replacing with the rotor?

ALSO, is there a discount code out there any where?
link http://www.rockauto.com/catalog/x,carcode,1232019,parttype,1000006

RAYBESTOS Part # 7032R {Professional Grade Outside Diameter 10.97" / 5 Bolt Holes (***FREE Backpack & Gift Card Plus a Chance to Win a Laptop!!! See Promotions & Rebates Page for Info***) #7032}
Front

thanks, LAWFISH

10.87" is the normal size for stock late A-body disks (10.97" may be a typo - I wouldn't worry about it). 11.75" diameter rotors would be an upgrade, but you'll need the right adapters for that size and your caliper type.

Right and left rotors are the same.

Get new bearings and pads, bearing grease, caliper grease, and spindle lock cotter key.