I'm trying to locate a Sharp CB probably from the late 60's (bought
second-hand in 1972). It worked both in-car when inserted into a
bracket (a plug in the bracket went into a socket in the back of the
radio) and out of the car off batteries in the radio. It had an
extensible antenna in the radio, and a fold out carrying handle. It
was a crystal set, and must have weighed over 5 pounds.
Has anybody seen or used one of these?

I would look at ebay. Type in vintage CB radio.
I find a lot of old CBs listed.
I can not believe some of the prices.