Crank pulley spacer question

[5.0 Nostalgia]

I need to order a crank pulley spacer for my motor but am confused on which one to get. There are two sizes that Ford Racing makes: .950" and .875." I am using the SFI Ford Racing harmonic balancer and most likely will be using March underdrive pulleys.

Thanks

 

[5.0 Nostalgia]

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