I purchased my 2007 Avalanche a few years back and just completed a 6L80 swap. (Love the new trans) The old 4L70 had tags that make me think it was a replacement, I?d like to know if so when was it put in service. What I?m trying to find out is the previous service history if possible so I don?t do things that might have already been done, really want to find out if the motor is original.