The old Bulletin Board has been removed from the server. And with recent "spring" cleaning, we are removing links back to it. The BB is still out in cyber space (to some extent) thanks to The Wayback Machine.
Has anyone tried to put in a 6x9 speaker behind the dash of a 55 1st series 3100 without using a plate attached to the radio?. I have a RetroSound radio and don’t want to hang speakers in the kick panels or up in the dash on either side of the cab.
Judging by the length of the RetroSound shafts (tuner, volume etc.), they are not long enough to mount a speaker panel. Regardless, the RetroSound shafts are not strong enough and would probably break from the weight. You will have to make your own speaker brackets. On the left side is an dash brace going to the firewall. GM used this brace to attach a mounting bracket. On the right side, unfortunately, I have no idea.
One thing about a cowl vent. If open and rain happens, your radio and speaker can get wet. I would fabricate a shield of some kind for protection.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."