Yea, I'm confused as well. Without a doubt everything about the front suspension and brakes are different between the two and will not interchange. Everything is smaller and mounts differently on the early cars including the a-arms and ball joints. So you now have 74 spindles on a 73??? Hmmmm.......
Yes I do. I have done my homework and have found that on the 73 at least, there is some interchange with the Mustang II. Using Autozone, Rock Auto, Kragen and other part websites, I do look for pinto parts, but will also look up a 76 Mustang II for the same part. Interchange may not be listed, but will sell the same part for both applications. The ball joints are the same in both applications. Here is a picture of the difference in the spindles. The drop spindle is about 3/4" taller causing my a arms to not be even.
I believe in 74, there was more space between the a arms to account for the difference in height for the spindle. With what I have done, it has created positive camber. If there is no more room for adjustment at the alignment shop, I may need to go with either an adjustable upper or lower arm, but I am not there yet.
Looking at pictures of 74 suspension, I may be tempted to try to install the lower or upper arms as the method of installation looks close to what I have. If someone has some lying around and is interested to see if it fits in a 73, let me know. Taking it apart is easy, but involves either Pandora or a can of worms.
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