Sub connectors for 1964 Plymouth Valiant

these are probably the "best" that are reasonably priced, but a little involved to install. 63-66 Mopar Plymouth A Body Frame Connectors

i like the old MP connectors, they're a bit crude but they install easy and do what they're supposed to and they're cheap. i don't know if they make them any longer, but mancini had their "house brand" version of them, so maybe?

these look interesting, and i know hotchkis makes good stuff
https://www.hotchkis.net/product/1963-1966-dodge-plymouth-a-body-sub-frame-connectors-dart-valaiant/
if you have a convertible and don't have torque boxes, i'd recommend those to go along with the connectors.