Using a Union Query to join multiple tables together w/ different fields

The following is a union query that actually utilizes a database link from an external source.

select classstructureid circuit_type, cinum, status, ciname, usccnumber, circuit_id, circuit_name,facility_number, sdf, channel, tcic, null as dacs, null as segment, null as ring_id, trunk_member, null as capacity, null as line_coding, repair_vendor, repair_vendor_phone, TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "LAST_RUN_DATE" from necom.msl_pln_circuit_ds0@necomprod union select classstructureid, cinum, status, ciname, usccnumber, circuit_id, circuit_name, facility_number, sdf, channel, tcic, null as dacs, null as segment, null as ring_id, trunk_member, null as capacity, line_coding, repair_vendor, repair_vendor_phone, TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "LAST_RUN_DATE" from necom.msl_pln_circuit_ds1_t1@necomprod union select classstructureid, cinum, status, ciname, usccnumber, circuit_id, circuit_name, facility_number, sdf, channel, null as tcic, dacs, segment, null as ring_id, null as trunk_member, null as capacity, null as line_coding, repair_vendor, repair_vendor_phone, TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "LAST_RUN_DATE" from necom.msl_pln_circuit_ds3_t3@necomprod union select classstructureid, cinum, status, ciname, usccnumber, circuit_id, circuit_name, facility_number, sdf, channel, null as tcic, null as dacs, segment, sc_id as ring_id, null as trunk_member, null as capacity, null as line_coding, repair_vendor, repair_vendor_phone, TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "LAST_RUN_DATE" from necom.Msl_Pln_Circuit_oc_all@necomprod union select classstructureid, cinum, status, ciname, usccnumber, circuit_id, circuit_name, null as facility_number, null as sdf, null as channel, null as tcic, null as dacs, null as segment, null as ring_id, null as trunk_member, evc_cir as capacity, null as line_coding, repair_vendor, repair_vendor_phone, TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "LAST_RUN_DATE" from necom.Msl_Pln_Circuit_ethernet@necomprod union select classstructureid, cinum, status, ciname, usccnumber, circuit_id, circuit_name, null as facility_number, null as sdf, null as channel, null as tcic, null as dacs, null as segment, null as ring_id, null as trunk_member, null as capacity, null as line_coding, repair_vendor, repair_vendor_phone, TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "LAST_RUN_DATE" from necom.Msl_Pln_Circuit_wan@necomprod union select classstructureid, cinum, status, ciname, usccnumber, null as circuit_id, circuit_name, null as facility_number, null as sdf, null as channel, null as tcic, null as dacs, null as segment, null as ring_id, null as trunk_member, port_speed as capacity, null as line_coding, repair_vendor, repair_vendor_phone, TO_CHAR (SYSDATE, 'MM-DD-YYYY HH24:MI:SS') "LAST_RUN_DATE" from necom.Msl_Pln_Circuit_mpls@necomprod