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Discussion Starter · #1 ·
Greetings all and a joyous Merry Christmas to those that celebrate it.

Heading pretty much sums it up. What vehicles and what years (with what engine) was a 4.1 ratio available in the 12 bolt Isuzu rear axle? I am considering installing a 4.10 rear diff, if avaiable, into my vehicle - I already have the 4.1 ratio in the front axle ( viewtopic.php?f=4&t=58037 ) and for now to save time, I am considering just installing a 4.10 in the rear axle and not touching the front axle/suspension (I have a 4.556 front diff available). I realize that I could swap in a 10 bolt rear axle (I still have the original 10 bolt axle with sheared teeth on the pinion) if I got another 10 bolt rear diff.

If I know what years/models then I can surf salvage yards w/ on line inventory to find the 4.10 12 bolt rear diff.
 

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Any 2wd Isuzu pickup with a 2.6l 4ZE1 engine should have the 12-bolt 4.10 gears you need, and you only need the 3rd member, not the entire axle assembly.
Other vehicles also have the right rears, but these are easy to identify, if the engine is missing look for rear disc brakes.
 

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oldestisuzuist said:
Any 2wd Isuzu pickup with a 2.6l 4ZE1 engine should have the 12-bolt 4.10 gears you need, and you only need the 3rd member, not the entire axle assembly.
Other vehicles also have the right rears, but these are easy to identify, if the engine is missing look for rear disc brakes.
just remember the 1 Ton long bed has the 2.6L and 4.30 gearing...i know its a rare model but its 2wd, 2.6L and not 4.10s....
 

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Discussion Starter · #5 ·
Thanks all, I ended up dropping the front axle and putting the 4.556 diff back in since I could not find a 4.10 rear on short notice. I read hru the zu4x rear axle web page and found an error. The 12 bolt rear is listed as having rear disc. My 12 bolt, was pulled from an early 90s Amigo had drum brakes. Its part of why I thought I had a 10 bolt in the rear the 10 and 12 bolt axles look so similar (I was expecting the 12 bolt to visually look much beefier than the 10 bolt.
 

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the amigo drum IS a 10 bolt, the 12 bolts are discs. the amigo you got it from was a 2wd 2.3L 5 spd correct?
 

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aribert,

Lowzone and the http://www.zu4x.com/modules.php?name=Co ... age&pid=21 site is correct for the 12 bolt. Perhaps you are confusing the 10 bolts you found on the external third member, while we refer to 10 and 12 bolts found on the RING gear, (internal). My Amigo, for instance, happens to be 2WD, but has the 2.6L engine and a 12 bolt, disk brake rear, stock. Believe this may be true for Troopers & PU's of same era. I see you have a 2.3L(4ZD1). They came stock with the 10 bolt/drum brake rear. You could upgrade to a beefier 12 bolt, not so easy to break! So, if you go to a a 2.6L (4ZE1) engine upgrade with a MAU trans., you will be set for robust wheeling!

Also, if you don't have "G80" on your firewall option plate, you most likely have an open rear. Visiting your local JY, may yield an LSD (G80) rear 3rd member from Troopers through '97. The trucks did not have 10 bolt G80 option, only 12 bolt. Possible projects ahead of you! 1989-1994 Amigo's are a good axle source to fit yours. Most Amigo's lacked G80 rear 3rd member, except on special order, but many 2nd gen Troopers to '97 and Acura SLX's do and it will bolt right in the Amigo 12 bolt rear axle!

Hope this helps,

GB
 

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ok, there is the GM 10 bolt and Isuzu 10 bolt. the GM 10 bolt was in the PICKUPS and 91-92 Rodeos (ALL). the Amigo should have the 10 bolt IF 2wd and 2.3L/5 spd combo ONLY. as soon as it got the 2.6L it got the 12 bolt disc rear. the pickups, ALL automatics, 1 ton and 4x4s had disc rears with 4.30s or 4.56 (4x4 w/big tire package). the GM 10 bolt can be identified by the removable rear cover plate, much like the Dana 44s in Rodeos. NOW, you CAN use a Dana 44 from a 93-95.5 Rodeo but the ebrake cables will be a PIA to hook up AND the snout on the Dana 44 (drive shaft flange) is longer so a shorter drive shaft MAY be in order. Troopers from 88-91 had the 12 bolt disc rear BUT the frames were narrower so they dont bolt in without changing the perch locations. I had a RS (4.77s) here and its 1.5" narrower on the leaf pack overall width. i wanted to swap in the whole rear into my pickup. wouldnt work. so i pulled the third member to swap into a pickup/amigo rear housing. now Amigos, rodeos and pickups ALL have the same width on the perches and all use the same length Leaf springs. they all interchange. just different spring rates. Clear as mud, right???

any 88-95 pickup amigo rodeo info needed, just PM me or post. im full of useless info and have loads of parts :)

the site is wrong about the 8bolt front. only up to 87 Pups had them. 88-95 were ALL 10 bolts front axles on the 4x4s, all were 4.30s (225/75/15) or 4.56s (31" tires).
 

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X2 what Ron said! He's got a ton of 1st hand experience.

GB
 
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Discussion Starter · #10 ·
My '92 Amigo originally had a 10 bolt rear axle - 4.10 ratio. THis is a picture of it:
When the diff sheared a tooth back in '09 due to fore/aft gear ratio mismatch (I put a 4.556 front diff when I converted to 4wd back in '99, I was unaware of the mismatch) I tried to buy a 12 bolt w/ a 4.556. THe only salvage yard I could find in my area that had an early Amigo / Rodeo w/ a leaf spring rear axle had this axle:
I was bummed that I could only find a another 10 bolt.

So this fall I set about to install a matching 4.10 front diff and that is when my 4wd became inoperable see this thread: viewtopic.php?f=4&t=58037 I was CERTAIN that I had a 10-bolt - after all the junkyard axle had drum brakes! Stupid me, I actally saw the Amigo that the purchased axle came out of (before the axle was pulled), but since it was a drum axle, I did not even bother to note the year or the option codes (from what I remember, it was a 2wd, 2.6L). After all, eventually I was going to get a 12-bolt.

So late in Dec, once the reality set in that I had a gear mismatch that was causing the binding as noted in the above thread, I first noticed the difference in the castings between the original axle and the junk yard axle - not that the 10 bolt has 2 long bolts the junkyard axle does not. Also late in Dec, I pulled the diff out of the junk yard axle and counted the teeth - a 4.556 ratio! BTW, I was in such a rush to get things back together that I did not even bother to count the teeth on the ring gear - but J. Lemond sent me a message back in 09 that the 10 bolt only was available in a 4.10 ratio - so I take it that my junk yard axle is a 12 bolt. So over New YEars, I undid that problem that I created in the fall and reinstalled the 4.556 front diff (and today I actually got to use it for a couple of blocks of unplowed snow (did not **need** it but wanted to make sure everything was OK). I had literaly been praying that the snows would not come until Christmas break (so that I could get my Amigo drivetrain sorted out) and my prayers were answered.
 
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