at US National Archives
Hacker, David,private, company I, regiment 37, DOD 1863, place Reg. Hosp., cause of death typhoid fever - Registers of Deaths of Volunteers, 1861 - 1865 Iowa, P-Z [bad label], Vol 16 of 63 page 23 aka image 27
US National Archives may have a Compiled Military Service Record file for David Hacker. These files are paper, not microfilm so unlikely to be available anywhere else. You can post a question at History Hub and perhaps someone has an interest in the regiment. https://historyhub.history.gov/welcome
The CMSR is an envelope (a jacket) containing one or more cards. These cards typically indicate that the soldier was present or absent during a certain period of time. Other cards may indicate the date of enlistment and discharge, amount of bounty paid him, and other information such as wounds received during battle or hospitalization for injury or illness. The soldier's place of birth may be indicated; if foreign born, only the country of birth is stated.