1974 Brain Box saves the day.

What I use you can easily find it on e bay.
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This what you can put in the back of these box's.

I just bought some NOS aftermarket boxes....Silver Streak (made in the U.S.A) out of Troy, MI that gotten hot in the box's would like to clean them up and use them. Was wonder if a person could melt the old stuff out and put new stuff in...is this what you're showing the folks here with this stuff?