Maybe it's not what I'm looking for! In that link, there are the insurance companies with the 75 year old age limit.
“ For Visa type : Non-O (Retirement), Long Stay O-A, O-X , STV , a separate Health Insurance Policy is required. The limit sum insured for In-Patient is not less than THB 400,000 and for Out-Patient is not less than THB 40,000 ”
To apply the Online Health Policy, please click https://longstay.tgia.org