GM A Body's, 67 Down VS 68 Up...

[pitts64]

Is there a big difference between the two? I can go either way now, I always thought the 68 up was a better suspension... Is it any different?

Thank you,
Jeff

[UMI Tech]

The 67/68 split requires a different length shock up front and the upper spring bucket is slightly different (hydroformed spring locator on early car, flat pad on newer car, although most of us spring manufacturers don't worry too much about the early pocket). A-arms are interchangeable. Sways are interchangeable but specific early vs late if you're a perfectionist.

The upper rear crossmember is in a different location. The early car requires 12-15/16 upper arms while the newer car is 10-1/4.

I don't know if the early car is better or not. We have good success with both platforms and they are pretty interchangeable except for what's noted above. There may be more if someone else chimes in...

[andrewb70]

The later cars have a shorter wheelbase...take that for what it's worth...

Andrew

[UMI Tech]

Oh, and a slight track width change (Data not verified, just what I found on the interweb)

1968-72 rearend is 1-inch wider [each axle is 9/16" longer], than the 1965-67 rearends ...
According to: [Chevrolet by the numbers 1965-69]-&-[Chevrolet by the numbers 1970-75] ....

1968-72 Chevelle [55 1/4"] axle tube flange, to axle tube flange ... axle shaft length [30 1/8"] ....
1965-67 Chevelle [54 1/4"] axle tube flange, to axle tube flange ... axle shaft length [29 9/16"] ...

[kevmurray]

My understanding is the rear wheel wells are significantly wider in the 68-72's.

[Nicks67GTO]

My understanding is the rear wheel wells are significantly wider in the 68-72's.

275/60/15's on an 8" rim are good fit in my 67 GTO. Same wheels and tires swim in my 70' Chevelle.