B737-300 CREW HAD LARGE DIFFERENCES BTWN THE CAPT AND FO IAS AND ALTIMETER.

Narrative

CLBING THROUGH 10000 FT; THE FO CALLED FOR ECONOMY CLB SPD. I ATTEMPTED TO EXECUTE HIS REQUEST; BUT THE SPD LINE ON THE CLB PAGE WENT BLANK. WE THEN NOTICED A SIGNIFICANT DIFFERENCE BTWN THE CAPT'S AND FO'S AIRSPD INDICATORS (APPROX 50 KIAS) AND ALTIMETERS (APPROX 2000 FT). WE CONTACTED ATC AND REQUESTED A BLOCK ALT WHILE WE SORTED THROUGH THE PROB. WE DETERMINED THAT THE CAPT'S INSTS MATCHED THE STANDBY INSTS. UPON REACHING CRUISE ALT ACCORDING TO THE CAPT'S INST; WE NOTED THAT THE PRESSURIZATION SYS INDICATED THE CORRECT CABIN ALT AND DIFFERENTIAL. WE CONTACTED DISPATCH AND MAINT. WE CONCLUDED THAT THE FO'S INSTS WERE INCORRECT AND THAT WE STILL HAD 2 INDEPENDENT SOURCES OF CORRECT AIRSPD AND ALT INFO. WE ALSO CONCURRED THAT THE FLT COULD CONTINUE ON TO ORD SAFELY. THERE WERE NO FLAGS OR WARNINGS ON ANY OF THE AIRSPD INDICATORS OR ALTIMETERS. ALL OTHER NAV AND ATTITUDE INSTS WERE NORMAL. I ASSUMED THE DUTIES OF PF; AND THE FLT CONTINUED TO ORD WITHOUT FURTHER INCIDENT. THERE WAS A GREAT DEAL OF DIALOGUE BTWN THE FO AND MYSELF. HE ASKED A NUMBER OF PERTINENT QUESTIONS AND HELPED INSURE THAT WE COVERED ALL THE BASES. ATC WAS VERY SUPPORTIVE WHILE WE DETERMINED WHICH INSTS WERE CORRECT. DISPATCH AND MAINT WERE ALSO GREAT RESOURCES.