Tony... first... Welcome to the Forums... we hope you can find just about anything you need here! then... a restored
1982 pickup? Geez... my first new car was a 1974 Dodge! Why... a 1982 truck is hardly broken in yet! And last... there wasn't anything built in 1982 that was worth restoring by ANY auto maker!
What kind of truck is it? Can you post photos? We love to see photos here!
Ok... <wiseguy off>... that round pin connector was pretty much all that was available then (I had it on a '77 F250 Supercab with my '70 Safari from 1987 through 1993), and it's commonly found on big-rig trucks to connect their trailers to the tractors. You can find those connectors at any truck stop or truck supply house. I would recommend changing it over to the Bargman style seven pin flat though as that's the defacto RV standard now, and the odds of you finding an RV today with the round pin connector is pretty slim. Keeping the round pin connector on your truck will prohibit you from pulling any trailer except the one you wire up to mate to it. Further, replacing the connector ensures that all of the wiring is good and nothing's corroded to the point that it won't work.
AIR 2053 Current: 2006 Born Free 32 RQ Kodiak Chassis, & 1995 Coachmen B-van
Former Airstreams: 1953 Flying Cloud, 1957 Overlander, 1961 Bambi, 1970 Safari Special, 1978 Argosy Minuet, 1985 325 Moho, 1994 Limited 34' Two-door, 1994 B190 "B-Van"