You guys are both wrong....

 

99-07 classics have a 24x tooth . . . rear cam sensor
the 07-up trucks (NNBS or GMT 900s) have the 58x tooth . . . front cam sensor

 

Now you understand why the parts guy said it wouldn't work. He isn't an idiot, he is going by what the computer says for legal liability and warranty reasons. Not everyone knows everything about ever single vehicle. I was a counter guy at a salvage yard for years. I offered as much interchange information as I was able, but there was no way I could flat know everything. Nobody does, you just do your best.

If someone came in and said they wanted X part for Y vehicle, and the computer told me it wouldn't work, I would still sell the customer the part, but tell them they couldn't return it and no warranty implied. The people that knew their stuff didn't care. If your wondering why someone would buy a transmission or engine without a warranty, that is because they usually got to see/hear/drive the vehicle before it was pulled.

 

Yep exactly what I said. It's a liability