[DeadheadNM]

Thanks for posting. It seems that Flint began building 72s with double walls like St Louis then shortly into the model year began installing single wall tops. Briefly, the typical style tubs were used with single wall tops and these K5s used the external speaker. After these the Flint tubs had the pickup style speaker location. If interested, here's a thread where I've tried to tease out details: http://67-72chevytrucks.com/vboard/s...d.php?t=701826