Dartmouth is in Bristol County. Probate records are kept in Taunton MA.
Probate & Family Court
Taunton, MA 02780
Main Telephone (508) 977-4970
Established 2 June 1685 from Plymouth County
Registry of Deeds for Dartmouth are kept in New Bedford, MA.
Registry of Deeds (Southern District)
25 North 6th Street
New Bedford, MA 02740
(508) 997-4250 (FAX)
Recording Hours: Monday - Friday 8:00AM - 4:00PM
The Southern District includes the towns of Acushnet, Dartmouth, Fairhaven, New Bedford and Westport.http://www.mass.gov/courts/courtsandjudges/courts/probateand...
Hope this helps out.