Mastiff/lab pup or younger dog wanted

We have a friend who just recently rescued a lab/mastiff pup from a shelter, and he is by far the best mannered little guy we've ever seen. She was able to adopt him for a very minimal cost through a local shelter, but we've now found that this mix is not commonly in shelters around us. We live in SE WI. We have 2 dogs now, but one, a Catahoula Bulldog (big as a mastiff) is quite old and will probably not be with us through the next winter. Our other, a terrier/lab mix, is about 3. Both are good dogs. We would like to bring in another dog so one is not alone, and we are not in a huge hurry. We live out in the country, about 900 ft. off the road, and also have 2 cats and 2 horses. Our boys are 12 and 10 and very sensible and attentive to the dogs. If you or anyone you know of has a mastiff/lab or a mastiff dog, please let us know. Vet ref. gladly provided. 262-949-4241

Thanks!