Ok, this is what I have, let me know what you think. I wasn't sure if I used the internal names on the correct fields or not:
<script language="javascript" type="text/javascript" src=" /sites/hp/JS/jquery-min.js"></script>
<script language="javascript" type="text/javascript" src=" /sites/hp/JS/jquery.SPServices-2014.01.min.js"></script>
<script language="javascript" type="text/javascript">
function PreSaveAction() {
var PCRNumberMain = document.getElementById('ctl00_m_g_7be96a6f_b09b_4ca7_acbf_624572c9b345_ctl00_CustomFieldIterator1_ctl00_ctl00_ctl00_ctl04_ctl00_ctl00_TextField').parentElement;
var ReleaseDateMain = document.getElementById('ctl00_m_g_7be96a6f_b09b_4ca7_acbf_624572c9b345_ctl00_CustomFieldIterator1_ctl20_ctl00_ctl00_ctl04_ctl00_ctl00_DateTimeField_DateTimeFieldDate').parentElement;
$().SPServices.SPUpdateMultipleListItems({
listName: "{11D7C2F8-8BCD-4EB8-A85C-10978D39BFED}",
CAMLQuery: "<Query><Where><Eq><FieldRef Name='PCR_x0020_Number'/><Value Type='Integer'>" + PCRNumberMain + "</Value></Eq></Where></Query>",
batchCmd: "Update",
valuepairs: [["Release Date", ReleaseDateMain]],
debug: true
});
} </script>