Which Alternator tension bracket for SB

[tparker]

Not sure if that is what it is called, but its the one on the bottom of the alt with the long channel for adjusting the Alt tension. Anyways, I see 2 different ones when I do a search and not sure I trust the sellers. There is one that is just a flat bar and another with a support arm that bolts to the engine. The Fastener Guide seems to show the flat bar for pre 1970 but isn't really clear on later ones.

Also, how do you identify the big block from the small block bracket?

Any thoughts?

[Mr Cuda]

The bracket with the support arm is for A/C .
Big block have a single crook, small block  are sweeping crescent  shaped.

[tparker]

Awesome, thanks.