Basic Auth Job Contact HTTP Post from Workato

Is basic auth allowed to do an HTTP post to Job Contact? My syntax appears correct but I am getting a 400 bad request.

{
Method: POST,
Response type: json,
Request name: Create Job Contact,
Request URL: https://api.servicem8.com/api_1.0/JobContact.json,
Request body: '{"job_uuid":"59f3b91d-177f-424a-8bf8-425604e5f20b", "first":"Homer", "last":"Simpson"}',
Expected encoding: UTF-8
}

Thanks