Hi Lisa, and welcome! Thanks for being interested in this old boy. Below is what his owner sent the nurse who's also helping save this old boy received...
We were told nearly three years ago that, like his sister, he also had kidney problems. She sadly died 18 months ago and we believed he would follow on soon after. As it turned out, his kidneys are fine ! He has a very mild heart murmur, a slightly over active thyroid so he eats regularly for a cat of his age and has a touch of arthritis in his hind legs. While the arthritis makes it hard for him to groom his hind flanks, it doesn't impede his movement and he is still perfectly mobile (still chases his tail from time to time!)
When beginning plans to move out of our house about 18 months ago, our backup was that our neighbours would take Sunny in the unlikely event that he was still here ( then believing his kidneys were failing). They have since taken in a pregnant stray cat and adopted her with one of her kittens - and are no longer be able to have Sunny.
We therefore find ourselves in the difficult situation of needing to find him a new home. He is a friendly, affectionate old boy and we will miss him sorely, but there is regrettably a no pets policy in the flat we are moving to.
A couple of pepole have offered a home to him, and I'm not sure if he'd be best as an only boy or not, I'll try to find out.
I will update the forum when I get more info. After the upheaval he's got coming, I am sure this boy will be so glad to be safe with a loving owner for his remaining time...