Basically, if it's a zero number ORI code, they are using the 4 digit before it. If not, they are using the last two digits before the zeros (all the ORI codes actually have two additional numbers (zeros) at the end, but I left them off). As RockeyNJ indicated, it's just easier to say...Here is a list for Morris County if it helps...
BOONTON NJ01401
BOONTON TOWNSHIP NJ01402 (42 cars)
BUTLER NJ01403
CHATHAM NJ01404
CHATHAM TOWNSHIP NJ01405
CHESTER NJ01406 (46 cars)
CHESTER TOWNSHIP NJ01407 (47 cars)
DENVILLE TOWNSHIP NJ01408
DOVER NJ01409
EAST HANOVER TOWNSHIP NJ01410
FLORHAM PARK NJ01411
HANOVER TOWNSHIP NJ01412
HARDING TOWNSHIP NJ01413
JEFFERSON TOWNSHIP NJ01414
KINNELON NJ01415
LINCOLN PARK NJ01416
LONG HILL TOWNSHIP NJ01430
MADISON NJ01417
MENDHAM NJ01418 (18 cars)
MENDHAM TOWNSHIP NJ01419 (19 cars)
MINE HILL TOWNSHIP NJ01420
MONTVILLE TOWNSHIP NJ01421
MORRIS NJ01400
MORRIS PLAINS NJ01423 (I'm guessing they will be 23 cars, but I haven't heard them yet).
MORRIS STATE POLICE NJ014SP
MORRIS TOWNSHIP NJ01422
MORRISTOWN NJ01424
MOUNT ARLINGTON NJ01426 (26 cars)
MOUNT OLIVE TOWNSHIP NJ01427
MOUNTAIN LAKES NJ01425 (25 cars)
NETCONG NJ01428 (28 cars)
PARK POLICE: MORRIS CNTY NJ01491 (91 cars)
PARSIPPANY-TROY HILLS TW NJ01429
PEQUANNOCK TOWNSHIP NJ01431
PROSECUTOR: MORRIS COUNT NJ01489
RANDOLPH TOWNSHIP NJ01432
RIVERDALE NJ01433
ROCKAWAY NJ01434 (34 cars)
ROCKAWAY TOWNSHIP NJ01435
ROXBURY TOWNSHIP NJ01436
SPT MORRIS CO NJ014PT
VICTORY GARDENS NJ01437
WASHINGTON TOWNSHIP NJ01438
WHARTON NJ01439 (39 cars)
Do you see the pattern now ?