Note: Regarding the Lancaster Town records on film #810,291 at the Salt Lake Family History Library. The film description says: Town records, vital records, 1653-1906. On the actual film, there are multiple parts and the date range covered by the different vital records vary as follows:
Item #1: Marriages 1737-1814; Births 1653-1816; Deaths 1654-1858. (These are in chronological order)
Item #2: Intentions of marriages 1856-1906.
Item #3: Births and Deaths 1743-1857 (These are in alphabetical order)
If you want records outside of these date ranges, this film will not provide them.
Film #2,259,293 has a bunch of other vital records for Lancaster, as follows, which all appear to be in chronological order with no index:
Item 2: B 1843-1905, M 1843-1853, D 1843-1857
Item 3: B 1906-1910
Item 4: M 1853-1905, D 1859-1905
Item 5: M 1906-1910
Item 6: D 1906-1910
Item 1 on this film is a published book: The Birth, marriage, and death register, church records and epitaphs of Lancaster, Massachusetts, 1643-1850 by Henry S. Norse, also available as a book with the call number 974.43/L3 V2b v. 1 and v. 2.