Muffler opinions...

[HIGHWAY BY THE SEA]

I am in the process of collecting parts for my upcoming new 350 motor in Grandtruck (1968). I was given a free pair of nearly-new Flowmaster 42441 mufflers. However, I have heard people say that these are LOUD. I like to be able to hear my radio and talk on the cell phone without pulling over and turning the truck off. So just how loud are these, speaking as one who has never heard them? And if they are loud, will installing them near the rear of my longbed stepside make the cab any quieter? I already have dual exhaust mufflers on my 1978 Jeep J10 directly under the cab and they are noticible, but not too bad (but not they are not 42441s either).