The Gaustad's I found in America are not your Gaustad's.
Here is the marriage in 1871 of your Gaustad's: #49 (That are the parents of Isak in 1873)
Source information: Oslo county, Trefoldighet, Banns register nr. 2 (1870-1878), Banns records 1871, page 16.
Permanent pagelink:
http://www.arkivverket.no/URN:kb_read?i ... x_side=-18
Permanent imagelink:
http://www.arkivverket.no/URN:NBN:no-a1 ... 020519.jpg
Groom name: John Isachsen Gaustad
Groom birth date: 1847
Groom age:
Bride name: Gurine Marie Halvorsen
Bride birth date: 1839
Bride age:
Residence: Oslo, Akershus, Norway
Event place: Trefoldighet Menighet, Oslo, Akershus, Norway
Event date: 03 Jun 1871
Father of groom name: Isach Johnsen
Mother of groom name:
Father of bride name: Halvor Olsen
Mother of bride name:
Groom prev wife name note:
Groom previous wife name:
Bride previous husband name note:
Bride previous husband name:
UDE batch number: M42833-2
Date range: 1858 - 1874
Record group: Norway-VR
Film number: 255761
Collection: Norway Marriages 1700-1900
Birth of Isach
Name: Isach Georg
Residence: Oslo, Akershus, Norway
Christening date: 02 Jun 1873
Christening place: TREFOLDIGHET MENIGHET, OSLO, AKERSHUS, NORWAY
Birth date: 14 Apr 1873
Birth place:
Father name: John Isachsen Gaustad
Father name note:
Mother name: Gurine Marie Halvorsen
Mother name note:
Gender: Male
Death date:
Name note:
UDE batch number: C42833-2
Date range: 1870 - 1876
Record group: Norway-VR
Film number: 255761
Collection: Norway Baptisms 1700-1900