[Danos]

I did this GVM (Granada, Versailles, Monarch) conversion on my '68 Fastback. I'm not 100% sure about '66 but I think it's an identical process and you'll need the same parts. I located the parts in a bone yard and my total cost was @ $150. The car now stops on a dime and braking improved dramatically. I love the conversion. I can't believe how easy and cheap it was. The spindles will bolt right up to the Mustangs upper and lower ball joints. I purchased new outer tie rod ends for a Granada. The hole where the outer tie rod ends connect to the spindle is larger on the Granada. There's no need to change the adjustment sleeve, unless it's worn out, because the Granada tie rod end fits the Mustangs Sleeve perfectly. I used the Granada Master Cylinder and proportioning valve with rear drum brakes. You should still be able to use this Master Cylinder but you might want to purchase an adjustable proportioning valve if you're going to rear discs.
BTW, If you're going to go through the trouble (really isn't much, I did it all in a Saturday) of the conversion, go ahead a rebuild the rest of the front suspension at the same time. In many cases the old ball joints aren't worth re-using or get damaged when separated from the spindles. Also some minor relocating of the brake hose/hard line fitting may be required.