Eventually, I would like to build a new wiring harness for the truck, but would like to preserve what is left of the original military harness. My curiosity was piqued as to whether I could find a new circular connector for the three lever switch so I wouldn't have to cannibalize the original. After hours and hours of searching, I may have some helpful information. The only references that I could find to the connector called it a MIL C 28-51 connector and some references to military stock numbers. I searched in vain for 28-51 connectors, so I decided to remove my three lever switch and look for part numbers. Those numbers didn't do a lot of good either, so I took some measurements from the connector and then did more searching.
What I have found so far is that the connector appears to be a MIL-C-5015 type of connector, shell size 28. These connectors are available with many different insert configurations. The three lever switch seems to use the insert type 28-51. Also, the cable end mating connector would be a type 3106 for the straight cable entry.
I have found several manufacturers that have MIL-C-5015 connectors in their product catalogs, but many list the 28-51 as a "special" insert, which I take to mean "we can make it if Uncle Sam gives us a contract". From the Amphenol catalog (and a few others), it appears to be current product.
Newark Electronics (www.newark.com) has these connectors (the Amphenol military version), with the 28-51 insert in their online catalog, under circular connectors. I haven't purchased one yet to see if they work, because 1) I am not ready to rebuild the wiring harness yet and 2) the prices range from about $70 to almost $200 and 3) they are listed as "non-cancelable/non-returnable". Newark's website shows that these connectors ship in 2-3 business days, so I think that you really can get it, but then again, they also ship directly from supplier, so maybe not?
I can't say for sure without buying one first, but I think I am on the right track. I was really hoping to find a commercial or industrial version rather than the military version to save money, but so far have had no luck.
Perhaps someone else may find this information useful.