O.K. The car is a 2001 Chevy Impala 3.4L with a 4t65e transmission (code "1RD"). The engine and trans have been replaced and were out of a 2003 Impala 3.4L. The code letters on the replacement trans is "3RD". I show both of these units to have 35/35/2.86 ratio... Login to read more.