Owner financing a corporation sell

[Rick Sims]

I own a 55 yr corporation, I want to sell it to a couple of my employees and owner finance. Trying to protect about a 4M loan. My last pay check!    I have talked to lawyers, financial advisers, insurance companies and searched online, I do not find what I am looking for.
I would like to know if there is any type of loan protection insurance anyone knows about in the US to protect such a loan. I know the rate will be expensive, there will be key man life insurance and all the personal guarantees. I just need to protect the loan if the buyers can't pay due to bad business economy or they become disabled somehow. There is no property attached to this sell, just the corporation and it's assets which are worth about $550,000.00.

Thanks

Rick