Our two most experts about diets are Growler and Sugarcatmom. I think there is a thread recommending kidney diets, but I don't think any of them are slices, but I could be wrong.
From this thread, post #11:
To stay within your grain/by products free wish other foods with good low phos numbers: EVO 95% Chicken & Turkey, Felidae Grain Free Salmon, Felidae Grain Free Cat & Kitten, Wellness Kitten, Wellness Beef & Chicken, Wellness Core Chicken, Turkey & Chicken Liver.
While not grain free but by product free and still with good low phos numbers: Felidae Platinum, Eagle Pack Holistic Select Turkey & Barley, Eagle Pack Holistic Select Duck & Chicken, Eagle Pack Holistic Select Chicken & Lamb, Felidae Chicken & Rice.