THE 1997 AND 1998 BLAZER HAS AN INHERENT DEFECT IN THE VALVE BODY IN TRANSMISSION. CODE 1870 FOUND AFTER VEHICLE IS WARM THE TRANSMISSION SLAMS INTO SECOND GEAR CAUSING THE REAR WHEELS TO LOOSE TRACTION. I WAS TOLD THE TRANSMISSION MOST LIKELY NEEDS A VALVE BODY. THE CHEVROLET DEALER AND A VERY REPUTABLE TRANSMISSION REPAIR SHOP ADVISED THAT THE 1997 AND 1998 BLAZERS ARE NOTORIOUS FOR THIS INHERENT DEFECT, AND THEY HAVE REPLACED THE DEFECTIVE VALVE BODY WITH A LARGER ONE WHICH FIXES THE PROBLEM. THE DEALER ADVISED THAT THERE HASN'T BEEN A RECALL PROBABLY BECAUSE NO ONE HAS COMPLAINED ABOUT THE PROBLEM.