Spindles for my 65 Dart?

Does you car not have spindles? If it does and it had 10" drums, you are good to go. If it had 9" drums that is a different spindle. The 10" spindles look fairly symmetric, so easy to mix up left & right (don't), whereas the 9" spindles have a thinner "goose-neck" more on the side (forgot which way, search google images). If you have a 1973+ car (always tell us), that is a totally different spindle (post 4, don't have 4 large bolt holes), plus you can't just bolt in a drum spindle since the upper and lower ball joints are different.

Others like Wilwood and Scarebird offer disks conversions for either 9" or 10" drums (different kits). Ask if SSBC does also. I don't recall seeing any after-market disk conversions for 1973+ cars. You could probably find used 9" spindles easier than 10", but not wise since they have smaller wheel bearings and the outer bearings on my 1969 Dart (9" drums) failed several times to spin in the hub and ruin it.