In just over a year I'll be 50 yrs old and plan to apply for a retirement visa. I have rental properties in Canada, and the monthly rental deposits to my bank account (in Canada) would be around 77,000 Baht/month (gross income). Anyone know if that is good enough, or will I need to provide an expense statement as well? (like mgmt fees, repairs, insurance, etc, etc...)

Many thanks.

Gross is required.

The docuemnts you need to provide are determined by your embassy. They decide based on what they will issue the confirmation letter.

Anyone know if that is good enough

You should check with your embassy. You need to get whatever form/affidavit they use to certify/verify or notarize your claimed income and present that to Immigrations as part of your application.

While NOT a requirement, a copy of your Thai bank passbook showing regular foreign sourced transfers may support your claim in the minds of the immigration officers.