Dobro serial numbers can be a real bugger to figure out -- not only because the numbering schemes have changed several times, but because there are a lot of numbers (like yours) that don't match any of the documented schemes.

Although it is one digit short, your number seems to most closely match the current Dobro numbering scheme, which would mean it was built in 1999 (post-Gibson):

1974-1979 OMI Dobro: Y (#)### D configuration.
Y is last digit of the year (if this number is "3" it is actually 1974).
3 or 4 numerals in center are instrument ranking for year starting with 101.
D is body type: D=wood, B=brass, M=steel or mandolin.

1980-1988 OMI Dobro: 8 (#)### yD configuration.
8 is the decade of manufacture (8=1980s).
2 or 3 or 4 numerals in center are serial number for year.
Numeral y before letter is last digit of year.
Last character is body type: D=wood, B=metal.

1988-1994 OMI Dobro: A# #### yyD configuration.
First letter (and numeral) is style.
Numerals in center are instrument ranking.
yy is last two digits of year.
Last character is body type: D=wood, B=metal, H=Hounddog, P=solid peghead.

1995-1997 OMI Dobro: A(A) (x)xxx yy configuration.
First letters are style.
Numerals in center are instrument ranking.
yy is last two digits of year year.

Gruhn describes it as "figured maple top, poinsettia coverplate, parallelogram soundholes, no holes in top at end of neck, squareneck, bound ebony fingerboard, lyre inlay, bound solid peghead, engraved pearl log, dark stain finish."