Hey guys, this is my first post in the rear end/gearing forum. I was curious, what is the difference between the 68-72 rear ends VS the pre 68 rears. Ive been looking around for a new rear for my 66 skylark and its much easier to locate the 68-72 10 and 12 bolts than it is the earlier years, so if it came down to it, what does it take to get the 68-72 rears to fit in a 66? Im assuming that relocating the mounting and spring perches to the correct location would do it, but Im not sure. Thanks for any help guys.
Greg, Read the article on the site below for the corporate 8.5" from 71-2 Skylark and Cutlass models. That is the best solution for your car and will be a direct bolt in!
You don't have to do anything with the spring perches. The later rear will just bolt in and the springs you have will work fine.
Greg, the width might be a bit different....my '66 GS rear is 61" wide drum-to-drum. '68-up is 62" wide..... except Chevelles, which are one inch narrower than the other GM's.....There are exceptions to this rule, so measure the rear before you buy. :Smarty: If possible, buy an 8.5" rear....they are stronger than the 8.2", and parts are more plentiful. As George suggested, check his site some great tech articles! http://www.buickperformance.com/page1.htm
Dave, both my '66 GS and '66 Special rears are both 61" wide....Like I said in my post, there may be exceptions, so measure first! BTW, to further confuse the issue, I have a '66 Chevelle 12 bolt and a '64 Olds that are 60" wide!........So measure, measure, measure!!
Well, I guess I stand corrected. The rear I removed from my 66 was the same width as the 72 8.5 I replaced it with. o No:
Thanks for the help guys. So, let me get this straight, although there may be a difference in width, basically any GM rear up until 72 will blot in . Or to be more specific, Im looking for an 8.5 inch 10 bolt, so if I find an 8.5 incher out of a 72 chevelle or a 71 el camino or cutlass......, it should bolt in my 66 as far as all the spring and mounting perches go. But there is always the possibility that it may be a different width? If thats the case, than things are looking good cause I dont mind if its a little wider or narrow as long as its within reason and can be fixed with different wheel backspacing(if necessary). My main concern is if I can expect it to bring it home and bolt it up as is, or will I need to cut and weld the mounting perches into new locations for the new rear to fit my stock suspension. Will there be any issues with driveshaft length, or will my stock lenght driveshaft unbolt from the 8.2 and bolt right up to an 8.5 without having to modify the length. Thanks guys.
The 8.5 A-body rear will bolt right up in any '64-72 A-body as long as following is taken into consideration... -stock 8.2, type "O" '67-70 Olds, or 12 bolt driveshaft will need to be shortened 7/8-1 1/8". The "nose" on the 8.5 housing, along with the pinion yoke are both longer & require the shorter shaft. -'64 model A-bodys used their own specific upper rear control arms & swapping in anything other than original '64 rearend will require use of '65-67 upper control arms. -'64 through '66 A-bodys used a different rear spring, than '67 & later. The '64-66's had a bolt on "ear" that clamped the rear spring down. One can trim the spring guides of the later rear & weld small square plate on then use the clamp on ears, OR one can go with later model springs. -Width issues... Width def changed DURING the '66 model year on BOP 8.2 rearends. Have ran across this in parting many '66 Tempests & LeMans & have been trying to track down exactly when this happened out of all the BOP A-body plants...for many years. Ck'ed our records & in so far custom building & selling now 317 early 8.5 A-body r/e's, the main tight fit issues I've run into were when installing 8.5 A-body rears under a pair of '64 Chevelles & a '65 Elco. The wheelhouses under the '64's & 65's are def the smallest of all A-bodys & customers in two cases were running 275-60R15's on aftermarket 8.5" (9.5" overall) wide wheels. Correct offset wheels were a must for such tall wide tires & even then, the tire-wheel combo is getting cose to the 1/4 panel lip. Never have run across this problem on a '66 or later, but on one of the '64's, we had to actually jack the Chevelle up with the shocks unhooked, bolt the wheel & tires on, then carefully let the body & chassis down & then reattach the shock mounts. Would not have had to go to this trouble with a 255-60R15 & a different wheel. Hope this helps. :3gears: Roger
Roger, You need to clear your PM box. I need to contact you. Or, please email me directly at GStage1@buickperformance.com Thanks!
