My suggestion is the following: WILHELM FRANCK is identical with JOHANN JOCHIM PETER WILHELM FRANK,born in Luetjenbrode,Schl.-Holst.,GER. Unfortunately I haven't got the exact date of birth. But I know that he married MAGDALENA CHRISTINA MESS on 11th December 1868 in the parish of Neukirchen. After that event they were not listed in the books any more,so my proposal is they may have emigrated to the USA.
His father was JOHANN GERHARD FRANK,who had his con- firmation 25th June 1806 in the Neukirchen parish.He married ANNA CHRISTINA DOROTHEA NICOLAUS on 25th Nov 1836.
His grandfather was THOMAS FRANK who was born abt 1751 and who was the tenant of a cheese and butter enterprise ("Holländerei-Pächter").He married ANNA MARIA DOSE on 17th August 1803 in the Neukirchen parish.He died on 30th December 1815 at the age of 64.His wife died on 13th November 1826.
By the way,it was quite common during those times to change the name FRANK to FRANCK.