Laravel 5.2 - Class 'GuzzleHttp\Client' not found, live only

I have my config/mail 'driver' set to mandrill, host, port, etc. including in services.php mandrill secret set.

Sending Mail works find locally, but on the live server I get: Class 'GuzzleHttp\Client' not found

I have tried "guzzlehttp/guzzle": "~5.3|~6.0", and then back to "guzzlehttp/guzzle": "~4.0", no luck. I have done composer update, and dump-autoload still no luck on my live server. Been through every other associated Stackoverflow question and still can't resolve.

via Chebli Mohamed