We are getting our lab from a rescue and all they know is that he's a lab and mixed. I would love to be able to figure it out before getting him if possible. They said he's a very good puppy, friendly and just very sweet. Unfortunately, this is all we've been told about his behavior. He is approximately 13 weeks old. Any help and ideas on his mix would be greatly appreciated.
You aren't going to be able to guess adequately till he's full grown. By then his appearance will have stabilized and behaviours that might be attributed to other breeds, that may not be apparent in his appearance, may have shown up. If I had to guess I might say some kind of hound based on the profile of his head in the third photo.
He looks little lost and bewildered in his photos, poor wee mite. Take him home soon, be kind to him, give him stability, love and training and he'll turn out to be a great dog no matter what his breed.