A quick google of that number finds this:
http://parts.digikey.com/1/parts/1159548-dsub-power-stb-21wa4-pin-dcl21wa4p500g40lf.html
which they don't stock but maybe they can order a "sample" quantity for you.
RS Components UK has them for pretty cheap, at £2.42 for 1:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=693-1042P&x=7&y=22
Their USA site doesn't list that p/n.
Cannon also makes a similar type of connector, in a few versions:
http://www.ittcannon.com/product.aspx?id=2278
and the power contacts are made for up to 40A.
An interesting type of connector designed for servo motors, that also handles up to 40A on the power contacts, is the CMx series:
http://www.ittcannon.com/product.aspx?id=1482
I tried to see if anyone had them in stock anywhere, but I seem unable to properly figure out their p/n schema.
For instance, Page 7 of the ComboD style (the first one) specs has a chart for figuring out what options create what p/n, but regardless of how I pick the options and search for a p/n, I get no finds even on Cannon's site, which has to be wrong, so I must not be using the right method of p/n creation. I *think* that you would want this one: DBM-E-17H5-P for the male side and DBM-E-17H5-S for the female side, to get solder cup versions you can bolt to a shell, but whether I use dashes or not, it doens't pull up anywhere.
These are some of the round Cannon connectors I was talking about:
http://www.ittcannon.com/MetaSearch.aspx?bq=Cannon&mq=&pq=Circular
These
http://www.ittcannon.com/product.aspx?id=1380
are the larger rectangular versions used as the interconnects for all power and data for the MD-80 flight computers, which are rather power-hungry things.
THey make a lot of connector types:
http://www.ittcannon.com/content.aspx?id=42