My wife borrowed the 2006 Silverado Duramax 2500 last night. She got in and it started like normal and stalled. Now it wont start. I can crank it for ever and nothing. Last summer it wouldn't start like this and I found it was the fuel filter needed changing. It has fuel but its low between 1/8 and 1/4 tank. I know there is an ATF leak, I was going to take care of that this weekend (I think its a hose near the radiator). Will a OBDII tell me anything? I'm going drive out to the truck and try it. The only other thing I can think of is the truck is parked on a incline - not very steep but still an incline. Is the there a low oil or ATF sensor that will keep the truck from starting?

Please help!