I ended up having to quit my job, then applied for SSDI and when received i never told the LTD carrier. I figured I had paid a few bucks per pay for the insurance and if they wanted their $$ they could come find me. So far so good 6 years later.....

Just put the $$ away and wait for them to contact you for payment.

I don't agree with Beachlover (sorry! )
In my situation I have it in writing that I am required to let my LTD provider knowif I have any income from jobs, State Disability, settlement awards, .... ANYTHING! If you don't I believe you are flirting with a fraud accusation.
Yeah, you could out that money away and wait but there's always a temptation to use it. What's the point in that unless you have it in a high interest account? The economy is in a bad place right now to even try that route. My opinion is to let all your income givers know about the other guys ASAP.

LTD is insurance, whether you paid for it or your employer provided it. Insurance policies list exclusions, provisions and often steps you must take when your situation changes. I agree that beachlover might find that it is more trouble to just let it ride, especially if there was a policy provision that immediate notice was required of other income sources. The only reason I could see that there would not be collection would be if the sdd began at the exact moment the ltd stopped, which would mean there was no overlap or overpayment.

If your LTD policy states that you must repay benefits when awarded SSDI, then you must. If you don't, when they find out and they will, you will pay back all benefits and interest. You won't be given a chance to do so over time, it will be immediate. They will probably use an interest rate that exceeds anything you can get on the money.

The problem I have ran into is my wife and I divorced at the time I was going to get my SSDI and the checks for the kids went to her. She would not pay the ltd back so I owe alot of money I don't have. Also I owe more due to the person at the ltd had told me that my exwife had paid the money back and I owe x amount of money. I paid them the x amount said and thought all was good. A year later they notice may exwife did not pay and they had paid to much and wanted back pay for that also. I don't have the money to pay them back. What can they do to me? I don't thing they can garnish my SSDI check, but I don't know.
Please let me know what they can do. I am going though all this at the time.