Hendrick has had a lot of development drivers over the year. Landon Cassill may be the one your thinking of, he actually ran in today's race and was running nicely until Biffle dumped him. Other Hendrick development drivers that they've gone through include Boston Reid, Blake Feese, Kyle Krisiloff, etc. All these guys came in really early and since everyone wants the 5 to run like it did when Kyle Busch piloted it they were gone. Bryan Clausen ran at Gateway last season for Ganassi and he just turned 18 the week prior. Maybe that's who you're thinking of.