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Discussion Starter · #1 ·
I know the 68-72 12 bolt rears are 1/2" shorter per side but it still bolts right up into a '66?? I guess I would have to get later model springs due to the '66 being a little different I think?? The cost of '68-72 are about 1/3 of what you find for '66-67 so I'm looking into alternatives.

Thanks
 

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It'll bolt right up. The springs mount over a thimble on the 68-72 version. Your 66 uses a retention washer, bolted to a mount on the bottom of the spring. I believe the springs interchange though.

Jerry
 

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The receiver at the top might be different IIRC. You will need to purchase for the body it is going in. Purchase for '66 regardless of what year housing you use. Someone with more experience on the '66 models will chime in for you hopefully.
 

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I know the 68-72 12 bolt rears are 1/2" shorter per side but it still bolts right up into a '66?? I guess I would have to get later model springs due to the '66 being a little different I think?? The cost of '68-72 are about 1/3 of what you find for '66-67 so I'm looking into alternatives.

Thanks
68-72 rears are actuall 1/2 inch WIDER per side. IT will bolt right up and even work better with alot of rear disc brake set ups with the emergency brake. If your wheels are close then you may have to go with more backspacing, but this really only applies to those trying to stuff every bit of space in the wheel wells with tire. I've got one from a 70 in my 67 right now. You need to keep 66 springs, because the perches arent any different on the axle tubes. Only the perches on the frame side are different. 67-72 springs have the pigtail coil on both the frame and axle side. 64-66 springs have the pigtail coil on the axle side only and are open on the frame side.
 

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The 68-72 housing are 1/2" wider per side than 65-67, They bolt right in but you might have to give some consideration to back space for some wheel/tire combos.

Check for clearance at the left upper control arm and the housing. 12 bolt left upper control arms are clearanced in this area so they won't rub but I've used 10 bolt arms with no rubbing issues.

Use 66 style springs, they fit the early frame pocket correctly and will fit the newer type housing spring perch.

:thumbsup:
 

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I'll just pile on and confirm what everyone else is saying here...

I just put a '70 12-bolt into my '66. It fit perfectly, the 66 springs slip right over the mounts on the later type rear. Of course I had to grind away part of the left upper control arm for clearance, and once I get my welder I'll pull it back out and weld a reinforcing plate over it. Otherwise this was a snap, as long as you have a little extra backspacing if you're putting wide rubber on it.
 

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Discussion Starter · #7 ·
I meant to say the later ones were wider, not shorter. Sorry for that. It sounds like a pretty easy bolt up deal. Thanks for all the replies.
 

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fwiw....when I replaced the axles on the factory 12 bolt posi in my 67ss, it turned out that since the build date is june 12, 1967 (late) - my car has the longer 68 axles/housing.....go figure. glad I went to summit with one in hand to measure - I just couldn't beleve it.. dont know about fitment because it has never been out of the car....
 
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