I'm looking for another letter of Pierre Deligne, this time to Jean-Pierre Serre (from around 1974 I think), in which he proves that the Galois representation associated to a certain Hecke eigenform is of specific form at p. This letter is mentioned, for example, in the remark 1.4 in here, or in the paper of B. Gross "A tameness criterion for Galois representations associated to modular forms (mod p)".
Additional question: Is it the same letter that is mentioned in Buzzard, Gee "The conjectural connections between automorphic representations and Galois representations"?
I will be grateful for your help.
edit: I'm pushing the question up. Does anyone have the mentioned letter?