I don't have a specific reference for this but it seems logical that the disclosure that is being referred to is the Notice of transfer and its required contents. Anything outside of this information and the model form would be institution specific information. If you are the institution that is transferring servicing to someone else you probably won't have much specific information that you can provide outside of the notice.
However, if you are taking over the servicing on a loan you may have more specific information you would want to provide in order to facilitate the consumers ability to make payments, such as available ways payments can be made and any costs or timing differences that might be involved.
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Opinions expressed are my own and do not reflect legal advice or the opinions of my employer.