debt

Since you have received a collection letter, you should immediately ask for debt validation within 30 days, else it would be considered that you owe the debt. Now, since you have made your last payment towards the debt in the early 90's, the SOL on the debt has already expired because the SOL in OK is 5 years. So the creditor cannot legally collect it.

check that---dont ask for debt validation. The debt is so old that I would simply send them a certified letter telling them to get lost. Tell them that the debt is so far past the statute of limitations that they have no legal recourse, and then tell them to not contact you again regarding this matter.

I agree. Send then a strongly worded Cease & Desist letter via Certified Mail, Return Receipt Requested. If they contact you again after the receipt of that letter, sue them. They do it because they are anxious to pay you $1,000 (for the flagrant FDCPA violation).

Also, file a complaint with the FTC and your State Attorney General.

Yes, the debt is too old and the creditor can never recover it legally. You should never make any payments towards the debt as even a small payment will restart the SOL and the creditor can again sue you to recover it. You should file a complaint against them with the FTC if they send you collection letters again or pull out your credit report.