Well, I think you have things to worry about than what's reported to credit reporting agencies. As your wife filed Ch7 BK she's has no financial responsiblity, but as co-signer they can come after you for any deficency - amount of loan + fees minus what they sell it for. And that's real easy to happen, they sell repossessed vehicles at wholesale auction and pad the loan balance with fees & charges.
What's the value of the truck (kbb.com) vs. how much you owe on it? If you've been paying on it for 28 mos. I'm guessing it;s worth more than you owe? Anyway you can come up with the $$$ they want? They can't report your payments on either of your credit reports because the debt was discharged for your wife & they don't report payments on co-signer's report. If they get a deficiency judgement against you that will most definately be reported on your credit report.
Is it possible for you to refi the truck away from that auto lender?
If you have been paying for 28 months you should be in a positive equity position or close to it by now. What is the make, model, year and milage of the vehicle? What is it worth? How much do you owe?
Dave is right about your consequences if you fail to catch up on your payments though. The refi is one possible long term solution - but there may be other options better for you.