Z_28_0117

In the VIS for my car, which is a history of all the work that has been done to my car by GM there are 2 entries which have no explanation any ideas what they are? I have found 0 in all the searches I have tried. Here is an excerpt form my VIS with the entries in question at the top. I did not own the car until 02/14/04.

06/19/2002 036254 # R0753 30030 miles
06/05/2002 036002 # R0752 29068 miles

01/03/2003 301216 # J5670 - SENSOR, MASS AIR FLOW - REPLACE 38631 miles

01/03/2003 301216 # L2300 - CONVERTER, OXIDATION CATALYTIC - REPLACE 38631 miles

01/03/2003 301216 D L2300 - CONVERTER, OXIDATION CATALYTIC - REPLACE 38631 miles

Dave89IROC

odds are, those were times that they couldn't find anything wrong, what is the next thing after those in time?