Hey guys. I was looking at putting a detriot locker in my rear, but a friend of mine said that a spool would be the same thing....only cheaper. so i looked into it and heres my question...What is the difference between a spool and a mini-spool(other that the obvious...price). It would be going into a 1987 Elky. Thanks guys

A mini spool is used mainly for cars racing on dirt tracks. A full spool is used for drag racing. Both kind of spools lock the axles together; they cannot be used on the street because when you go around a corner the outside tire has to spin faster than the inside tire. If you try to use a spool on the street you will either ruin the tires or most likely break something in the rear axle assembly. Don't try using a spool for street driving.

I agree. Spools make for some bad handling.

A Detroit locker is neither spool or mini-spool. It will release around corners, but makes a loud clicking sound.

Powertrax makes a quite locker (and a loud locker). ~$400, but you can install it yourself. The Detriot locker is about ~300.

A minispool replaces the gears in your carrier. I think a spool replaces the entire carrier.

I would not recommend either for street use. What type of rearend do you have? If you have a stock 87 rearend, it's not a Detroit locker you want.

Power Trax (http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=2006&prmenbr=361) has anyone tried this locking differential?

"What type of rearend do you have? If you have a stock 87 rearend, it's not a Detroit locker you want."
Yes as far as i know i have a stock rear-end, i havent looked into any parts yet because i jsut paid my loan off, but now that i have it paid off its time to upgrade and modify!!!! :D Why wouldnt i want to put a detriot locker in it. i dont plan on doing any 'legal' racing with it just maybe run it along a friends car, crown vic HA! A friend of mine said a spool would be just fine in my rear, and yes i realize that the tires will wear faster. Its still winter here in ND, USA so i have some time still 'cause i dont have a shop and i hate the cold very much. and im not really too worried about how the handling would be altered by a spool. well thanks for the help guys.

You cannot use a spool on the street! You shouldn't even think about it. Wearing your tires would be the least of your problems with a spool. Manufacturers of autos put differentials in the driving axle because you need it.

If i shouldnt use a spool in the rear-end what are my other options to make it posi?

I just ordered a powertrax. $380 shipped was the best price I could find from Rubicon4x4.com Best choice IMO, since I can install it myslef.

Next best choice is buying a complete, used, posi rear, but then you're taking chances. Not all can be rebuilt. I found this out when I bought a factory '87 MCSS 3.73 rear. It's an Auburn unit with a broken cone.


If you plan on changing the ring and pinion as well, get a Eaton and have someone install it.

ok thanks....
um what about a locker?

BTW, you have a GM 7.5" 26 spline rear.

92-0775-2605

i was looking thru the forums and someone else suggest a Eaton posi differential unit, they are like $350 off ebay(new of course). what you guys think of that?

I would think that the Eaton, Auburn, or PowerTrax are good choices, all three are available from Jegs; just pick the one you can get the best deal on.

Lockers are a little cheaper, but not enough justify putting up with the clicking. Find Powertrax's website, they do good job explaining both (they sell lock-rite lockers as well).

You can install a powertrax yourself. Add $100-200 to the price of the eaton or auburn for installation. (plus you can always pull the powertrax if you sell the truck)

$380 < $350+shipping+install

Rich, let us know how you like the powertrax when you get it.

I don't anything about the Powertrax, a Detroit Locker is for a Ford 9" rearend , an Eaton posi is rebuildable, an Auburn is not. If you plan on leaving your engine pretty much stock, the 7.5" rearend will survive until it just wears out...you can replace it with a Eaton or Auburn posi unit. Some other options that would be better than the stock rearend would be an 8.5" out of a Grand National, Buick Type T or Olds 442 G-body (these are bolt in and sell used if you can find one usually between $600-$800) also a 12 bolt Chevy rear can be used if you get aftermarket control arms. If you plan on modifying the engine, depending on how drastic you get, you definately want to consider something other than the 7.5"

Mike where can you get a 8.5 GN rear diff with posi? I've looked and looked and couldn't find one. If you have a source I would sure like to buy one. A while ago you had a message in which you said you had a source for modified 9" Ford housings real reasonable, can you tell us where?

Do I know where there's a 8.5" is right now...no...could I find one tommorow...who knows, probably! "Search" is a wonderful tool. There are other websites similar to ECC that deal with GNs' Type Ts' and 442s'. They also have their "classifieds section" I found ECC through "search". Anyway type in G-body websites in search and about 5 or 6 different websites dealing with GNs' and Type Ts' will come up. Look in the classifieds of those sites. Also check Ebay "parts and accessories" for differentials. It may take a couple of hours looking but I'll bet you could find a couple of 8.5s for sale at any given time using all the resources availble. There's a WEB RING also for G-bodies that probably lists several possible sources for finding one. It's been awhile since I looked for a 8.5''. I didn't like the idea of paying upwards of $600-$800 bucks (going price) for a rearend that might need to be rebuilt. I've decided to go with a 9" Ford. And yes I have a source for bolt-in 9" Ford housings. These are brand new bare housings set up for the new larger Ford bearings, they run for $280 + $35 for shipping. The guy that fabricates them is temporarily out because they had to get the rest of the shop work caught up. I just talked to him 3 days ago. He'll have a couple ready for sale soon...and sorry to say, I'm first in line, then I'll post his website here...sorry! I've researched this and I think that I should be able to assemble a 9" Ford for around $1350 minus the brake set up and using a Strange iron case and resplined 31 spline axles with a GM bolt pattern, most of the parts are availble from the the guy selling the housings. It would cost about another $200-300 for the brake set up depending on what type of brakes are used. This is almost $1000 less then what Moser, Currie, and a few others sell their assembled housings for minus the brakes.

Hey Mike what do you think of these brackets/spring perch? Speedway Motors 9" Ford Axle Brackets (http://www.speedwaymotors.com/xq/asp/strBase_List./hilt./source.2191/base_no.91048336/str_base_no.8025714%2C8026390%2C8026498%2C802837S4 86%2C80292417%2C8352701956%2C8352702189C%2C8352702 290%2C91043800%2C91044140%2C91045840%2C91045845%2C 91045850%2C91045851%2C91047843%2C910480%2C91048333 %2C91048335%2C91048336%2C91048340%2C/header_title./page_name.prod%5Flist%5Fdisplay%2Easp/search_type.L1%7E90/search_option./deptsearch./dept_id./dept_id_p./dept_name./dept_name_p./ShowImages.yes/sq.20/cont.1/intPgNo.2/redirect./qx/product.htm) Do you know what width axle housings will fit 5th Gen El Caminos? If I can get a 9" Ford axle with the proper width I could get into a Ford axle cheap.

Oh I also ran across this:Rear Disc Brake Kit for Ford 9" Housings (http://www.speedwaymotors.com/xq/asp/strBase_List./hilt./source.2192/base_no.8351406695/str_base_no.7211570%2C8351403425%2C8351406695%2C91 010308%2C91010309%2C91011550%2C91011560%2C91011588 %2C91011591%2C91012085%2C91012360%2C91012900%2C910 15145%2C910153%2C91015363%2C91015365%2C91015593%2C 91017110%2C91020107%2C91021003%2C/header_title./page_name.prod%5Flist%5Fdisplay%2Easp/search_type.L1%7E493/search_option./deptsearch./dept_id./dept_id_p./dept_name./dept_name_p./ShowImages.yes/sq.40/cont.1/intPgNo.3/redirect./qx/product.htm) The price seems very good especially since it includes 4 piston calipers. What do you think?

Buick Grand National 8.5" rearend for sale on Ebay...item #2465244118 nice, but expensive! 2 days left $600+

Thanks Mike. I'm going to contact the seller and see what the shipping would be to Hawaii. A local guy here is selling the rear axle assembly out of an !985 Monte Carlo SS. It should be an 8.5 with 3.72 gears and if it has posi I'll try to buy it.

Only Buick Grand Nationals, Type Ts' and Olds 442s came with the 8.5". Monte Carlos did not have them.

And only from 1984 and on for the 8½".


You have want to figure out your goals before shelling out money for an 8½. I plan on 13's for one of my cars, before moving on to another. For that, a 7½" should be plenty.

Yes they were 7.5". Didn't all '85 up SSs have 3.73 and most of them with posi?

Yes, all 7.5 . From what I have read, 85 up were all 3.73s but posi was still always just a option.