I have a plan for my '77 302 motor and auto trans now, but can somebody clue me in as to what differential I have? After reading your comments, I want to change to a better gear ratio, but don't have a clue if I have a 7", 8", or 9" in this beast. Any input would be appreciated. Can I put posi or limited slip in this rear end with bolt-in parts? If yes, what's the easiest way? Can I just order the parts from Summit or Jegs, and bolt them in myself, or is there machine work involved? I haven't done this stuff for 35 years, and so much has changed. Help!
You should have an 8" you can order posi for these but are some what more hard to find then for a 9" my advice it to get a used 9" rear end with posi it will probably be cheaper then buying the hard to find 8" posi.
Grant more than likely you have an 8" rear with a 2.79 or 3.00 gear ratio...check the tag on the hoghead to be sure. If you want to go to a posi and higher ratio there are companies that make the entire hoghead built to your specs. The names escape me right now but I'm sure someone here knows.
8" diff Thanks for the input on the 8" rear end. If I want to buy a 9" with posi, which model Ford am I looking for, and what year? Any idea about price? You folks are terrific!
The problem with a 9" is the only one with an exact fit is out of a Lincoln Versailles...very hard to find. My 9" is from an F-150 pickup that was cut and shortened, new Moser posi put in and 3.55 gears. After all was said and done I've got 900.00 in it. Do a search on E-Bay and see what an 8" hog head built to your specs will run. Think you'll find it's alot cheaper.
I was tracking 2 8" hogheads/pumpkins/center sections on Ebay this weekend and the one wtih 3.55 gears went for $480 and the one with 3.00 gears went for $295. Both jegs and summit sell powertrax units that you can install without disturbing ring & pinion steup for about $430 from either.
Thanks 77Mav302! That's what I needed to know. I'll search e-bay for what i need. Is there a supplier I should be looking for that isn't going to "shaft me" (all puns intended). I've heard of lots of corruption on e-bay, but there are supposed to be lots of honest people too. Any suggestions? Thanks again!
Finding a 9" to fit your car is much harder than building what you have. Early Mustangs (65-70) bolt right in too but good luck finding one. Unless your going to make some serious hp, the 9" aint worth the effort. Jegs sells Auburn and other lockers as mentioned. Currie also makes a limited slip like the Ford Trac-lock.
The 8 inch posi has gotten ridiculously high because its rarity. Try ebay, I just bought a fresh rebuilt with 4.11 richmond gears, but the price was tough...$550 plus shipping, but was a great alternative to changing the whole rearend.
I've decided to put a milder 3.55 gear set into my 8", and eventually install a limited slip or locker. Since this is my first street rod, I'm trying to go slow and ask lots of questions. Does anybody have a preference on locking units? Auburn and Eaton are two I've looked at, and there is a new Detroit locker that's supposed to be stronger, but I don't know much else. My Mav is a mild street machine, and I doubt if it goes down a drag strip. I don't think I need the "top of the line" unit, just a reliable one. Any opinions? (bad question for this group!)
I have an auburn pro series in one of mine and havent had any problems yet. One bad thing about these units are they are not rebuildable. Currie makes a Ford type Trac-lock for the 8" which is a great street posi unit and is rebuildable.
Grant, I think I have a 8in punkin with 3.55 gears. will have to look and make sure. Am sure it is an open one but have to check it out.
GRant, I installed a PowerTrax LockRite in my 8". With new gears, bearings etc.. total cost was less than $500.00 I have had great success buying from Jegs or Summitt. Both avalable with online hopping and free shiping on many orders! Scotty P
On rebuilding traction lok 8 and 9" , they use the same discs in both. The average price for the 8" has been in the $450 range for years and may be higher by now. Do some serching for complete units. Your well ahead with new parts ready to install. Setting up a rear yourself requires a dial indicator, mounting and a big bench vise to hold the whole unit while you put some big time torque to the ring gear bolts as well as setting up the back lash. For other rear ends, the Mav has the narrwest size there was used. Anything you use will be wider unless cut down or is close enough. In any event you will have to pay attention to how the spring pads handle the angle and make changes to correct as well as spacing. One late model rear you might want to look at is from an Explorer with leaf springs. Then you have the 8.8 size with all kinds of gear ratios as well as traction lock at much lower cost. As you can see, any way you go will result is more expense than you might think till the job is called done.
