62 steering ams with disc brakes

Why do you need to use the 64 steering arms(instead of the ones on my 62) when I change to camaro style disc brakes. they are so close in geometry. Im using 64 5 lug spindles with the upper boss machined down, everthing fits good but I know on some of the conversion instructions they say to use the later steering arms(64 in this case), is it necessary or not? thanks guys Ryan

Take your 62-63 steering arms and place them on your new disc brake spindles and the answer will be apparent.

now I have a pretty good guess at what it might be:)

The bolt spacing is different among other things.