Having just back fitted AC to a 6 pack motor for a friend....is your idle pulley lining up with the water pump and outer crank pulley? Angle of picture is deceiving. The reason I ask, the small cast 2 hole spacer also comes in different lengths depending on year. Additionally the 4 crank pulley come in slightly different size beside the asymmetric/ uniform hole pattern. 68ish? and down used a 5/8" PS belt, while 69ish? up used the 1/4" belt, which pushed the outer pulley out further. Hence the different spacer piece.
Idler and WP and Crank pulleys line up. It doesn't really look like it, but they do.
The spacer is irrelevant to the alternator problem, but still could be the wrong bracket. It is likely the bracket that came off that engine when it was in the '76 truck, but the engine is a '69. I can't tell you where all of the parts came from, but every thing looks the same as this kit.
https://dantesparts.com/i-30499102-...440-big-block-with-air-conditioning.html
