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Rear Axle Code

3K views 20 replies 7 participants last post by  DwadeCham 
#1 ·
So I finally got under the car and sanded off 50 years of gunk and undercoating. I got this code off the rear axle: FJ0325

So my understanding is that is 3.08 ratio that was made on March 25.

I know it is a 10 bolt. Not sure how to figure out what size. Wondering where to go from here. Just had the engine rebuilt and have around 400 horses to play with.


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#2 ·
#3 ·
It would be much easier to help if you include what year car you are working on. A photo from the rear showing housing would be good too., try this to help:

https://www.crankshaftcoalition.com/wiki/Rearend_identification


You are right. I should have taken one. For sure a 10 bolt. I will take one soon. Only pic I took was of the stamp but I think it isn’t helpful.


The car is a 68 Malibu. Originally had a 307 in it with a power glide.


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#5 ·
I doubt it was swapped. I guess it’s possible. This picture doesn’t help much but it was the best I could do with it on the ground.


Is there any point to upgrading an 8.2? Or should I just go for something else. I have a lot of other priorities over dropping $3000 on a 12 bolt.


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#10 ·
Do you think it is worth upgrading to a 3.55 or 3.73 from a 3.08 with that?

Hehe, someone got a little sloppy with a lot of things on this car. Realized yesterday the bolts for the sway bar bushings/connects aren’t the same. Passenger side spacer spins freely and has about 1/4 to 1/2 of play in it. The one on the driver side, which I assume is the correct one, is right and doesn’t have play in it. One is a coarse thread and one is fine.


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#14 · (Edited)
Everything really depends on what your goals are with this car: street, strip, road track, cruiser? With 400 ponys ( i suppose thats flywheel?) not rwhp. If its just street with a little fun I wouldn't hesitate to put a little money into your 10 bolt. I did, 1972 Chevelle, 350/350 3:36, posi, new bearings and seals, hardened axels, girdle, and brakes for less than 1K. Huge difference, great low end, stomped on it a few times - feels fantastic and moves the car pretty well. Don't underestimate that 10b.
 

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#16 ·
Eaton 10bolt posi units are readily available for these rears. We recently added on to my son's 68 4dr with a crate 350 and wide ratio Muncie. His car was also originally a 307/PG car. It's now somewhat of a sleeper, with factory air cond.



























Oh ya, and another thing that I like to do when I have a rear out of the car, is to add a magnetic drain plug. The LAST year Chevy installed a rearend drain plug was 1961.

I drill and tap for a 1/2in fine thread plug (same plug as used in oil pans). Then I use a die grinder with a sanding disc to make the area around the hole smooth and flat.




















I also install new buishings for the trailing arms while I have the rear out of the car. I made up a puller from misc parts, old bearing races, a length of all thread, etc, that I had around the shop.







 
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#18 ·
I would install some kind of overdrive trans. Makes street driving a lot more fun.

How about 3.73 gears and a 200R4 ? That would be a fun combo.

Great acceleration and good cruising too.

It takes special tools to work on a 10 or 12 bolt. I would ask around , maybe someone on craigslist ? I wouldn't do that myself. It's enough of a PITA to pull and reinstall that 10 bolt. >:)
 
#19 ·
I would install some kind of overdrive trans. Makes street driving a lot more fun.



How about 3.73 gears and a 200R4 ? That would be a fun combo.



Great acceleration and good cruising too.



It takes special tools to work on a 10 or 12 bolt. I would ask around , maybe someone on craigslist ? I wouldn't do that myself. It's enough of a PITA to pull and reinstall that 10 bolt. >:)


I would love that. I just had this powerglide rebuilt though. I had the engine rebuilt so I won’t be able to do anything that is very expensive for a while. I do want to do 3.73 though. If I could find a 200R4 at a good price it could work out.


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