Information about the album 'Letter to Evan' by Bill Evans is extremely limited and is not found in the standard official discographies of the pianist. There is no widely recognized studio or live album with that title in Bill Evans' catalog.
It is possible that 'Letter to Evan' is an unofficial recording, a bootleg, or a confusion with another title. Bill Evans did record a composition called 'Letter to Evan' (dedicated to his son Evan Evans) in some sessions, but not as a full album.
Due to the lack of verifiable sources, it is not possible to provide accurate data on producer, label, recording date, or track listing for an album titled 'Letter to Evan' from 1979. It is recommended to consult specialized catalogs such as Peter Pettinger's discography or the Bill Evans Webpages for clarification.