John, thats a smart looking truck you have there.
I would imagine that the trouble you are having, is that the space between knobs on the radio, is different than your dash right? I can't remember which is bigger right now. I have a GM 510 radio in my truck. What I did, was file the knob openings in the dash of the truck, to make it fit. The big chrome bezel fits on the outside, and covers this up. I have a GM radio just like the one you have there, for my Pontiac, just have to mount it, I've had it done for nearly a year! Boy, am I behind on projects! The big chrome surrounds I have for my two radios, do not have those sweet lines on them. I like yours!!
Now, I could have moved the knobs on the radio, as Truckernix says, but then the big outside bezel wouldn't fit. That's why I filed the dash. All the fitments are in the thing Fred will send you.
The GM 48 uses a double point vibrator, instead of a rectifier tube right? Did your original vibrator work yet? I found a NOS one I think will work for mine, didn't get it back on the bench before I started building my garagemahal, once thats done hopefully I can get caught back up on fun stuff!!
The two tube output is great. I wired the speaker in the dash, and a 12" in a big box behind the truck seat. The big speaker is full range, and came out of a defunct console radio, from the 50's. Man, what big sound when Perry Como sings in my truck! When its big band Jump time, it really is!
