I was able to dissect one page that has blank ad:

http://imcdb.org/vehicle_1266592.html

<script src="http://sync.1rx.io/usersyncall?impinit=1"></script>
<script src="http://cdn.adrta.com/r.js?rcb=1558994063587_154006&cb=5474468268#ro;paid=ro- ;avid=1243;caid=c-97r05e1tw;plid=cr-9fr12e1tw;siteId=232660;publisherId=18630;kv1=728x90;kv2=http%3A%2F%2Fimcdb.org- %2Fvehicle_1266592.html;kv3=RX-485cd589-5f85-4b9a-8558-a5584935475f;kv4=24.30.126.111;kv7=2013;kv11=6fe96cb71d54f01ab9067b0d6def19ad;k- v12=1237434;kv16=33.9306;kv17=-84.4622;kv18=;kv19=;kv23=;kv26=Windows%207;kv25=Firefox%20-%20Windows;kv27=Mozilla%2F5.0%20(Windows206.1%3B%20Win64%3B%20x64%3B%20rv%3A56.- 0)2F201001012F56.02F56.2.10;kv24=Desktop_Web_Banner;kv32=unknown" type="text/javascript"></script>
<script type="text/javascript" src="https://q.adrta.com/s/ro/aa.js?cb=5474468268#ro;paid=ro;avid=1243;caid=c-97r05e1tw;plid=cr-9fr12e1tw;siteId=232660;publisherId=18630;kv1=728x90;kv2=http%3A%2F%2Fimcdb.org- %2Fvehicle_1266592.html;kv3=RX-485cd589-5f85-4b9a-8558-a5584935475f;kv4=24.30.126.111;kv7=2013;kv11=6fe96cb71d54f01ab9067b0d6def19ad;k- v12=1237434;kv16=33.9306;kv17=-84.4622;kv18=;kv19=;kv23=;kv26=Windows%207;kv25=Firefox%20-%20Windows;kv27=Mozilla%2F5.0%20(Windows206.1%3B%20Win64%3B%20x64%3B%20rv%3A56.- 0)2F201001012F56.02F56.2.10;kv24=Desktop_Web_Banner;kv32=unknown"></script>
<script type="text/javascript" src="//rxcdn.1rx.io/js/banner-1.0.61.js" roneflag="C3EA9A8B-0564-4203-B3F4-3974489D02A6" placementid="1237434" sspid="2013" dspid="1243" pubid="18630" siteid="232660" appbundle="" appid="unknown" campaign="c-97r05e1tw" media="site" device="desktop" userid="RX-485cd589-5f85-4b9a-8558-a5584935475f" useridorig="RX-485cd589-5f85-4b9a-8558-a5584935475f" domain="imcdb.org" ip="24.30.126.111" ifa="" cc="US" dealid="" requestid="6fe96cb71d54f01ab9067b0d6def19ad" traffictype="Desktop_Web_Banner" throttlerate="0.047348" adservedomain="a-nj.1rx.io" divid="63f2be65d03431cdef4e4b6f01ee5d76-6fe96cb71d54f01ab9067b0d6def19ad-9949826f44d7def1965c7dca743e8726-78d60b548a6750678797bd48f0868216" ua="Mozilla%2F5.0%20(Windows206.1%3B%20Win64%3B%20x64%3B%20rv%3A56.0)2F20100101- 2F56.02F56.2.10" includedpartnerproducts="partner:Pixalate|product:Pixalate|method:JS,partner:Qu- antcast|product:Measure|method:JS" gdpr="false"></script>
<iframe src="https://pghbl1.pubgalaxy.com/proxy/?provider_id=215&price=0.1&location=ct2- 6st26city26dma26zp26bw%3D4&adunit_code=2F.2_9723.3_imcdb.org_tier1&size=728x90&d- ata_type=1" scrolling="no" marginheight="0" marginwidth="0" allowtransparency="true" is-ren="true" height="1" frameborder="0" width="1"></iframe>
<iframe style="display: none; visibility: hidden;" src="//a-nj.1rx.io/trackedevent/doc?doc_type=thirdpartybeacon&doc_version=8&ssp=2013&dsp- =1243&pub=18630&site=232660&appid=unknown&appbundle=unknown&placementid=1237434&- requestid=6fe96cb71d54f01ab9067b0d6def19ad&userid=RX-485cd589-5f85-4b9a-8558-a5584935475f&useridorig=RX-485cd589-5f85-4b9a-8558-a5584935475f&domain=imcdb.org&ifa=unknown&cc=US&dealid=unknown&traffictype=Desk- top_Web_Banner&gdpr=0&productlist=partner:Pixalate|product:Pixalate|method:JS,pa- rtner:Quantcast|product:Measure|method:JS&starttime=1558994063634" is-ren="true"></iframe>

This was extracted from Waterfox 56.2.10 (64-bit) browser.