Simplest possible implementation
For each customer (ie bodyshop / MSO / entity):
Have them generate an API key and share it with you
For each repair record for each of those customers:
Using the bodyshop’s API key, send a JSON message formatted according to the specification, containing:
Customer name
Customer phone number
Your GUID for that record
Any other fields you want to send us
Whenever any of those fields update, send us the same again