So I had so much trouble finding these differences all over the web and figured maybe I can help some one who thinks there trucks messing up or that there doing something wrong I ordered two key fobs on eBay who claim oem internals and a aftermarket casing claiming that If your FCC is AB01502T that it will work and that part number 16245100-29 it'll all work good so long as your vehicle has AU0 RPO code this isn't true for my 97 the company even claims that 16245102 is a new part number and I wondered why if it's so scarce to find but the internals are different but they do have same FCC numbers and the one from eBay didn't work but 3 inches away at advance auto parts remote tester I have yet to try the new or a different key to see. But here are pics of internals big difference well if any one needs help free to text me 575-942-3527 I'm not sure if my pics uploaded