Unimusic owned Ampeg in 1969 when the SVT was first sold. The early cabinets had the brown stained baffle. In November of 1971 Magnavox bought the company. New owners like to change things. They switched to the black baffle around 1973. They also changed from a four-pin connector to a ¼" jack so the back plate is different.
Official Ampeg Portaflex Club #89