Differential Type

Thanks. now another question 1980 had the Lerado and the Renegade i believe mine is the lerado due to the tilt steering is this a true statement or is the info i read wrong.
 
Don't quote me on this, but '75 or '76 saw the AMC20 come into use, and it was in EVERYTHING until 1986 when the CJ got a Dana 44 rear again.

The 1986 is the ONLY 'Wide Track' Dana 44 for the rear.

Also, I believe ALL the CJ5 's were Narrow Track, no matter what year, but I could be proved wrong on that too...
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Anyway, kind of oddly 'Diamond' shape and 10 bolts, it's a Dana Differential.

Round and 'Bubble' shaped with 12 TORX BOLTS, it's a AMC (Spicer) Model 20 differential.

The FSJ and CJ Model 20's are different.
The FSJ 20's have thicker tubes, better (larger) bearings and better seals.

The CJ AMC 20s have weak, thin tubes, tiny little wheel bearings, two piece axles and a dozen other things that make them weak.

The AMC20 Center Section and the actual Differential Carrier, the Ring & Pinion Gears, ect. were all of sufficient strength and could hold their own.
It was the CJ version of weak tubes, bearings, 2 piece axles, ect. cause them to be a problem.
 
Team Rush I believe you are correct all CJ5 's were narrow track, at least thats what I know.
Not to hijack but rather suggest another thread. TR could you elaborate more on the pros and cons, upgrades for the M20.
 
As far as I'm concerned there are no cons for the upgrade's to an AMC20 , if you want to use one, the upgrades are a must. The center section is strong, arguably as strong or stronger then a 44. It's the stupid weak tube joints and flanged axles that are the problem. Why the hell they ever did that I'll never know... Well, we know it was $$$... :)

Put in a good flanged axle kit and reinforce the tubes (weld them) and you have a very sturdy axle. More then capable of handling most V8's and 33's. Of course any axle can be broken but a properly upgraded 20 will last a long time barring serious abuse.
 
I just picked up my AMC20 from my Jeep guy. It has moser 1 piece shafts 4.56s and a lunchbox locker. The tubes are welded at the centersection. Look for a good diff cover also , the stock ones are like aluminum foil if you play in the rocks.
 
There is nothing wrong with a 20 when a little work is done on them. 1 piece axles are a must, and a little spot welding at the housing / tube. My buddy went a step beyond, and cut 2 pieces of 3/8" steel to work as trusses and welded them from the pumpkin to the tubes. It was a damn strong rearend and took a hell of a beating.
 
I have has a lot of success with my 77 CJ5 with a T-18 , Chevy 327 35" tires and the M20. It has Moser forged axles, and a go rhino truss/skid plate, stock Limited slip.
On my CJ2a I am upgrading from a D41 to an M20. So far I have alloy axles, lock rite, BTF cover. I would like to find a weld on truss for above the axle that will tie into the cover.
As far as welding the tubes; spot weld to the cast iron, weld all the way around to the iron, or drill the iron and tubes and plug weld?
 
If you plan on keeping it, it would be best to rebuilt it. But especially if you rebuilt it or get a new one, put Royal Purple Synthetic Diff. Oil in it. Jeeps love it plus it will run really strong.
Source(s):

Jeep Owner. I run Royal Purple in everything on my Jeep
 
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