Ring and Pinion questions

OK, I know we use a Corporate 10 bolt up front and a 12 bolt in the rear, but does anyone know if these are the same as GM 10 bolts and 12 bolts. The reason I ask is because I have been finding these(GM) with thick and thin ring gears, which is what some people in older posts said we needed. I am also unable to find out what size our 10 bolt ring is, because I keep finding GM 10 bolt rings in 7.5", 8.2", and 8.5". Am I way off the mark by thinking we can use GM ring and pinions? I thought I read somewhere that Isuzu was partnered with GM a while back. Could someone also tell me the counts of the pinion splines on each one? I thought I had heard 17 somewhere, but that sounded kind of low so I'm not sure.

I am going to guess on this question, so take it for what it is worth. I don't think Indy 4x would have made 5.38 gears for Isuzus if something already existed for them - no advantage to that. Otherwise, I would like to know where you found out we use Corp 10 and 12 bolts? The GM Corp's are not a 3rd member design and the bolt count signifies how many bolts are on the diff cover to my understanding. Did you find something different? The depth of the pinion shaft from 3rd member to GM housing could be very different, not to mention the possible difference in diameters, and bearing locations.


It is a novel thought though so don't let what I say get in your way - that would be awesome if you found something nobody else has found over the last 15 years! Good luck in your search, man!

I found out we use Corporate ring and pinions from this site while doing searches for "differential" and "gears". I also read that the bolt count is off of the ring, not the covers, so I guess that is another thing someone can hopefully clarify. The reason I am curious is because in my searching SPAZZ and/or Swordy mentioned the use of 4.88's which I had never heard of on an Isuzu, but surprisingly they show up when you look up some the GM ring and pinion sets. Along with, you guessed it, 4.56, 4.30, 5.38, among others. There are just a lot of things pointing in this direction it seems. If you do the searches I mentioned and dig through the posts, I think you'll see.

I searched a little bit outside this forum and have grown quite curious about this now. Thanks alot! However, I haven't found anything close to addressing what you would like to find out more about. My guess is, it can't be done... now use it as motivation to prove me wrong! :p


I might be able to look at my front 3rd member today to see how many splines are on the pinion. If I remember, I'll let you know what it has.

Not anything to do with the GM axles.

These are Isuzu 10 and 12 bolts.

The rear is between a 44 and 60 for strength, depending upon which version is under the VX, I know Troopers of the same vintage had the larger modified versions... (I dont believe the VX had the wider track on it, and utilizes the early version, but Im not 100% certain)

Early 12-bolt (more common):
* ~56" or ~58" wide
* 1.32" diameter, 26-spline shafts
* ring gear roughly sized like a Dana 44
* differentals: open, clutch-plate LSD, ARB (RD44)
* gears: 4.56, 4.77. 5.38 (Tera)

Late 'Modified' 12-bolt:
* ~60" wide
* 1.50" diameter, 23-spline shafts
* large, ~9.75" Spicer-produced ring gear (ala D50) ring gear - roughly same size as a 60
* differentals: open, clutch-plate LSD, ARB (RD85)
* gears: 4.30 (5.38's available Internationally)
* little bigger brakes

The front is 17 spline, ~8" ring gear.

The ring and pinion I believe should be something like 43/9 with the pinion having somewhere around 30 or so splines on the end opposite where it contacts the ring. I have done some more research as well, and the GM and Corporate names mean the same thing. I have also read several places that the 10bolt/12 bolt reference means the number of bolts holding the ring gear in place., not the differential cover or third member. I wonder if they use the same internal gears even though the GM diffs aren't third member designs. I would also like you to check if you get the chance the diameter of the front ring. It seems there are several different diameters for this listed under GM 10 bolts. If this stuff does end up matching up, then we have seriously stumbled upon something awesome.

My gears are the 4.77's though. Does that matter to you? I am not sure if the diameter is bigger than the stockers or not.

The diameter isn't any different, it's just the number of teeth in each piece. The ring on yours I think should be 43 teeth, and the pinion I think is 9. I think the stock gears are only lower but a tooth or two in comparison. All the other sizes should be the same for interchangeability.

Well, I haven't completely unpacked my tools and I can't find what I need so I gots no info!

Oohhhh man am I steamed. I finally found and ordered the 4.78 from some place back east, and found a front differential off a 99 amigo from some wrecker on ebay. The setup from ebay came yesterday, and I cracked it open to make certain the gears were correct. They were 4.10's which led to this: :_mecker: followed by this : :_brickwal and finally: :waab: :_crying: I talked to the company today and they told me the set had been mislabeled and that they didn't have a set of 4.78's anywhere. They are having it picked up by United Package Smashers tomorrow morning. So now, hopefully the set for the rear will be legit. I'm not holding my breath.

Ohhh.... That blows! How do you mislabel something like that?! That doesn't seem right at all.... :confused: Sorry that didn't pan out for you - better just go solid axle! :p

Solid axle, yeah, not for quite some time. And definitely not me first. I like going off in weird directions with stuff, but a SAS is a little over my head and my budget. Besides, sooner or later, this is going to be my offroad rig.
http://www.vehicross.info/gallery/data/500/sugga.jpg
http://www.vehicross.info/gallery/data/500/sugga2.jpg

What is that? A Gaz? I am sure it is Russian... am I wrong? :confused:

Swedish actually. It's a 1954-56 Volvo TP-21 "Sugga" or sow in swedish. They were a military command/radio car designed to be able to operate from the tops of snowy mountains to get the signal out, so the 4wheel system kicks *****. They only made a little over 500 total. People I have talked to have re-engined them with 350-454 V-8's, and quite a few diesels as well. There was actually a german company who restored one and did a fantastic job including a frame off restoration, a BIG growling diesel swap, a lift with bigger tires, full disc brakes, and some other modern amenities. It was awesome to say the least. They are somewhat expensive and a PITA to import. It's more of a long term interest I have been pursuing for quite a few years now. I am just waiting to start driving semis at UPS, then I'm gettin' one for sure!!! Here's a link to the video from the german guys.

http://redirect.streaming.szm.de/red...05/gos_320.wmv

Hey, are you still interested in the spline count and diameters and all that stuff? I took my front 3rd apart last night - everything looks great!!! But I can measure whatever you need now, so let me know. It is 43:9 teeth count. I'm still tempted to swap in a 44 though - I N D E C I S I O N