Can you tell me if Low Boy Hot Water Heaters are available for natural gas, we are looking to relocate ours into a crawl space, and we can only do this if we can use a low boy

Sure are, natural gas and LP. Check with a plumbing supply or big box store, saw them today at Home Depot.

See https://www.askmehelpdesk.com/plumbing/gas-hot-water-heater-80600.html

Can you tell me if Low Boy Hot Water Heaters are available for natural gas, we are looking to relocate ours into a crawl space, and we can only do this if we can use a low boy
Low boy hot water heaters are about 48 inches high. I have been searching for months for a 36 inch one for replacement. I hear Rheem and AO Smith make a 48 inch one. Good luck.

If anybody out there knows where I could get a 36 inch one, please let me know.