i am using these items for in the case distro:
bus bar - screwed into case (its wood, used screws included)
pre made tails- (could make your own, see last link)
im sure there are better 12v 2.1 hoodas but i felt these were decent copper quality (?)
JACK-- not the cheapest but it mates with a locking plug.
https://www.mouser.com/ProductDetail/502-L722AS-
the bushing on this one is a little short IMHO so i use this NL d-series panel, with the RCA removed. - (loosen nut on rear to remove)
Neutrik NF2D-B-2 RCA Jack D-Series Red/Black.
You could use any d-sub rca or bnc size and be fine i think.
using the d-series is also nice because the connector then sits flush(ish) with the side of case and less chance of getting whacked off whilst being in your trunk or truck.
https://www.mouser.com/ProductDetail/502-L722A
is supposedly a longer bushing but the specs place it same as the AS.
both take a dust cover 
https://www.mouser.com/ProductDetail/502-JCAP
-this connects with, if you want locking-
–PLUG
https://www.mouser.com/ProductDetail/502-767KS17 (lg diameter cable)
https://www.mouser.com/ProductDetail/502-767KS15 (med diameter cable)
https://www.mouser.com/ProductDetail/502-767KS12 (small diam cable)
–cheaper ($2.00) not locking plug but still not the cheapest ( i have a few and cross threaded less than the CUI part on mouser for approx 1.30 or so.)