How to Tell which Axles I have?

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CSFJ

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That should have the corporate 10 bolt up front, and either a semi float or full float 14 bolt in the rear.
 
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marks86

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dana 44- Front only.. came on early k5,k10,k20, suburban

10bolt- Front- Came on newer style k5,k10,k20, suburban

dana 60- Front Only.. Came on k30 only

10bolt- Rear- k5,k10(weakest rear axle)

12 bolt- Rear- Came on k10HD,k20s,

14 Semi- Rear- k20 and suburban only(correct me if Im wrong)

14 Corp.- K30 some k20HD and Suburban

dana 70- k30 Dually Pickup only(non cab and chassis)
 
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1984 never used a Danna 44 in 79/80 they went to the corporate front 10 bolt on everything except 1 tons.

most 3/4 tons in the 80s came with a 12 bolt rear prior to the 80s it was most commonly a 14 bolt

My 87 came with 10 bolt front and a 14 bolt SF rear

I would bet that you have a 10 bolt front and a 12 bolt rear

Both the 12 and 14 bolt SF axles come in either 6 or 8 lug axle configurations. The 10 bolt rear is only a 6 lug

Count the number of bolts on the cover of your rear axle. 10 is 10 bolt,12 is 12 bolt and 14 is 14 bolt. I can pretty much guarantee that you have the front GM 10 bolt

There is no such thing as a 12 bolt FF

If you have a 14 bolt FF it will have a hub that sticks out through the center of your rim and will have I believe 6 bolts on the end of it that hold the axle flange to the hub.

If it is a SF it will be flush at the center of your rim with nothing sticking out through your rim
 
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MadOgre said:
If you have a 14 bolt FF it will have a hub that sticks out through the center of your rim and will have I believe 6 bolts on the end of it that hold the axle flange to the hub.



If it is a SF it will be flush at the center of your rim with nothing sticking out through your rim
Click to expand...


Very helpful!
 
bucket

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MadOgre said:
1984 never used a Danna 44 in 79/80 they went to the corporate front 10 bolt on everything except 1 tons.

most 3/4 tons in the 80s came with a 12 bolt rear prior to the 80s it was most commonly a 14 bolt

My 87 came with 10 bolt front and a 14 bolt SF rear

I would bet that you have a 10 bolt front and a 12 bolt rear

Both the 12 and 14 bolt SF axles come in either 6 or 8 lug axle configurations. The 10 bolt rear is only a 6 lug

Count the number of bolts on the cover of your rear axle. 10 is 10 bolt,12 is 12 bolt and 14 is 14 bolt. I can pretty much guarantee that you have the front GM 10 bolt

There is no such thing as a 12 bolt FF

If you have a 14 bolt FF it will have a hub that sticks out through the center of your rim and will have I believe 6 bolts on the end of it that hold the axle flange to the hub.

If it is a SF it will be flush at the center of your rim with nothing sticking out through your rim
Click to expand...

There was no 8-lug 12 bolt. 12 bolt axles were only used in 1/2 tons until around '81 or '82. 3/4 ton trucks and Burbs got the 14FF until about the same time, then the lighter optioned trucks got the 14SF and heavier optioned trucks still got the 14FF.
 
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bucket said:
There was no 8-lug 12 bolt. 12 bolt axles were only used in 1/2 tons until around '81 or '82. 3/4 ton trucks and Burbs got the 14FF until about the same time, then the lighter optioned trucks got the 14SF and heavier optioned trucks still got the 14FF.
Click to expand...

Untrue!

My dad has an 84 with a factory 3/4 ton 12 bolt with 8 lugs and I almost bought one for a project last year with the exact same set up. It was an 82 camper special 3/4 ton 12 bolt 8 lugs.
 
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MadOgre said:
Untrue!

My dad has an 84 with a factory 3/4 ton 12 bolt with 8 lugs and I almost bought one for a project last year with the exact same set up. It was an 82 camper special 3/4 ton 12 bolt 8 lugs.
Click to expand...

!!!

I assure you it's not a 12 bolt axle if it has 8 lugs. ANY 3/4 ton truck or Burb in the 80's had either a 14SF or a 14FF. Go count the bolts again.
 
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Im not stupid! It is a 3/4 ton 12 bolt 8 lug axle my friend! Yes it is!
 
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And its not the only one out there!
 
CSFJ

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It was always my understanding, that the "bolt #" designation, came from the number of bolts on the ring gear, not the cover. If this is the case the 9.5" sf 14 bolt has 12 bolts holding the cover on. Perhaps this is where the confusion is coming from?
 
CSFJ

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Hopefully the image posts.
 

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No they are called by the number of bolts on the cover. 10 has 10 12 has 12 and both the 14 bolt SF and FF have 14 bolts on their cover.

Plus the cover is quite different from a 12 to 14 bolt SF

A 3/4 ton 12 bolt axle is the same SF design. the only difference is that they have 8 wheel lugs on the axle flange.
 
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