i currently have the 8inch original in the car. i guess its a 3.0:1 . i am thinking of 3:5's. something more getup and go, but not overly nuts. any sugestions? is there a good doner to pull from, and what should i look for?
I believe a 3:55 ratio for your application would be a good choice. You did not indicate an ultimate goal, that might require a more aggressive ratio. Checkout the information on the website at the following link. Pay particular attention to the paragraph addressing pre and post 1967 8" differential center sections and their ability to withstand punishment. Contrary to the statement in the article a post 1967 8" differential can handle more then 300 HP in a light car such as the Maverick or Comet. http://www.hemmings.com/mus/stories/2008/05/01/hmn_feature23.html
If you're saying you'd like to pull unit that already has a 3.50, good luck... Even back in '60s they were not very common unless maybe bind a 4-speed, but even then was often a 2.80 or 3.00 ... It isn't that hard to bust one of the early cases, good traction and a 4000 RPM clutch drop, BAM! It's over(seen it done by more than one 289)... With a automatic and small amount of saneness, likely be OK...
I got mine from a guy selling them on eBay, with new gears, yukon billet trac lok, and a 1 year warranty. I picked it up locally and traded in my old chunk to save some money. Over 4000 miles on it no problems. My engine setup is similar to yours, so we are probably putting out a similar amount of power. The carrier alone is around $500, so seemed like a good deal to me. And yes he only uses the later style cases. http://www.ebay.com/itm/8-INCH-FORD...m4d3d9f06c2:m:mjKfkAl3du038g3PQ5qLd-w&vxp=mtr
Even if you do find a center section from the earlier cars with a 3.50:1 already installed, the odds are that the center section (or chunk) is not going to have a fill plug/hole, as the earlier housings had the fill plug in the back of the housing. I ran into this EXACT problem with my friend's V8 Pinto project. He had a Maverick rear axle in the car, bought an old Fairlane rearend with 3.50:1 and was going to just swap the chunks, but we ended up buying a Yukon bearing kit with Timken bearings, and changing the ring and pinion and putting the 3.50 ring and pinion in the later Maverick case with the extra webbing AND a fill hole.
Bomrat You may want to check out your local bone yard and look at mustang II I have pulled 3.42 and 3.55 gears out of these cars.
I have an extra chunk with either a 3:80 or 4:11 gearset. I'll count the teeth and see. If you'd be interested. I just swapped in a trac loc 4:11 unit and this was an extra I had.
I've never seen a 3.42 or 3.55 in any 8" Ford/Mercury... You sure you weren't pulling GM rears??? Hollander verified there was never a 3.42, Pinto & StangII did get a 6¾" rear with 3.55, 8" were 3.50... There were some Pintos & StangII with 3.40 8" units... Yeah it's splitting hairs but like a 3.31, the 3.42 & 3.55 were never used in a 8" or 9" from factory... the 3.55 are common in 7.5" & 8.8"...
I don't know where you get your info BUT I have pulled 2 sets of 8" 3.55 and 1 set of 8" 3.42 for mustang II with factory tags on them ( if there were no tags on them I would not wasted my time pulling them ) .
The 8-inch rear that came in Mustang-IIs was available in a 3.55 ratio (V-6 models). 3.50 is a 9-inch ratio. 3.42 is a GM ratio. Ford offered 3.40.
Ford never offered 3.42 in any 8 or 9-inch rear-end. You probably misread the tag and it's likely a 3.40. Counting the teeth on the ring and pinion is the only true way to know.
