Parse multipart/related response and save attachment to file - node.js

Question

I'm doing a simple POST that returns the below. I'm expecting a .txt.gz file. I need to know how to retrieve the attachment. I've tried creating a buffer, delimiting, and splitting before writing the file, but it always comes back as corrupt.
The request library explains how to consume a PUT request for an attachment, but not how to consume a response back.
Can anyone help? Been at this for a week now.
JSON.stringify(res)
{
"statusCode": 200,
"body": {
"type": "Buffer",
"data": [
13,
10,
45,
45(..truncated)
]
},
"headers": {
"set-cookie": [
"JSESSIONIDSSO=982EF51351B9497045DB6AB5A2D50DBF; Path=/; Secure; HttpOnly",
"JSESSIONID=995EF8A4A893860159CE463582E4CDDD; Path=/logcollectionservice; Secure; HttpOnly",
"SoapSession.id=-2851099334472488788"
],
"x-frame-options": "SAMEORIGIN",
"strict-transport-security": "max-age=31536000; includeSubdomains",
"content-type": "multipart/related; type=\"text/xml\"; start=\"<852C508C64251E692C9217DFA4EB7433>\"; boundary=\"----=_Part_109_17473961.1526352793275\"",
"transfer-encoding": "chunked",
"date": "Tue, 15 May 2018 02:53:13 GMT",
"connection": "close",
"server": ""
},
"request": {
"uri": {
"protocol": "https:",
"slashes": true,
"auth": null,
"host": "50.22.22.22:8443",
"port": "8443",
"hostname": "50.22.22.22",
"hash": null,
"search": null,
"query": null,
"pathname": "/logcollectionservice/services/DimeGetFileService",
"path": "/logcollectionservice/services/DimeGetFileService",
"href": "https://50.22.22.22:8443/logcollectionservice/services/DimeGetFileService"
},
"method": "POST",
"headers": {
"Authorization": "Basic YWRt123123123123123123",
"SOAPAction": "http://schemas.cisco.com/ast/soap/action/#LogCollectionPort#GetOneFile",
"content-length": 467
}
}
}
res.body
------=_Part_183_12814895.1526363698144
Content-Type: text/xml; charset=UTF-8
Content-Transfer-Encoding: binary
Content-Id: <5DDAB109C3B14685FF6B0EA83D2CF8E4>
<?xml version="1.0" encoding="UTF-8"?><soapenv:Envelope
xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><soapenv:Body>
<ns1:GetOneFileResponse
soapenv:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
xmlns:ns1="http://schemas.cisco.com/ast/soap/"><DataHandler
href="cid:36F92AA211EE04B422D4B07AB07D841A" xsi:type="ns2:DataHandler"
xmlns:ns2="DimeGetFileService"/></ns1:GetOneFileResponse>
</soapenv:Body></soapenv:Envelope>
------=_Part_183_12814895.1526363698144
Content-Type: application/octet-stream
Content-Transfer-Encoding: binary
Content-Id: <36F92AA211EE04B422D4B07AB07D841A>
����o�:���W��U����<��퐖.�I��8!h�0�l��?~���m�z��;'����>��oL���'Ϗ��3
'�tSV�EO�8zÂ���[a0����.��`�4wbO�q��FI���:�n܍>��e-
��!^#"�U5��;��^����U[V���s˽��q_��̣
����{gm����r��
���c��㬌Pf]Z�����cs���#ߵ� (truncated)
------=_Part_183_12814895.1526363698144--