Technical 53 Chevy 3100 Six lug diff swap question

Hi i am new to this forum as well new to these trucks. Im replacing the torque tube in the back and am looking for a six lug replacement differential that will be the same lug pattern. My goal with the truck is to look pretty much stock other than being lowered and drivetrain . It will be a cruiser with a 350 supported by a th350. Any suggestions?

 

No need to replace the entire rearend. You can swap in a 3rd member from a 1955 to 1959 Chevy truck. A direct bolt on to the original rear end.

 

There is bit more to it than that. Chevy torque tube rear ends have a pivoting mount bracket were they are clamped to the leaf spring. Those pivoting brackets must be replaced with a standard, non-movable spring pad when deleting the torque tube center section.

There are a number of 6 lug open drive axle choices, should you also be interested in a axle gear ratio change. Certainly '55 thru about '69/'70 Chevy & GMC trucks, Jeep full size pickups and wagons and several OT late model Nissan/Toyota, etc. trucks and SUVs.

Ray

 

Take a look at the Toyota 4Runner/Tacoma rear- same pattern and can take the power of a 350 (just don't get one from a 4 cyl truck)

 

Add some ladder bars and you can leave the pivoting bracket as is.

 

Will a truck 3rd member fit in pre 55 cars

 

There are ones from late 60's and early 70's Chevy trucks that had 6 lug. The truck 12 bolt could be used but you may want to check out widths first.

 

a quick list of Chevy truck 6 lug rears...
-62 and older are mostly 3.90 ratio, except for some A/T that could be had with 3.38. These are removable center gear chucks. Parts are not interchangeable with 63-up rears that went to integral gear carrier housing.

-63-ONLY is a mongrel rear. It uses one-year-only axle shafts, so if a bearing went bad and damaged the axle shaft, you will have a hard time finding a good shaft. And, the "bearing extender" repair bearing made for newer truck axles will not fit the 63.

-64-69 is the same through these years. And is about 1.5" narrower total, compared to 70-up, from wheel flange to wheel flange.

-70 2wd is still 6 lug, but went wider than 64-69 These are mostly 3.73 with a very rare chance of finding the 3.07 used on A/T, and some 402 big blocks

-71 2wd went to 5 lug, BUT 4x4 still uses the 6 lugs. It is same width as 70 2wd.

and your best selection of gear ratios start in early 70s with a 3.07 being about the lowest number, and not too hard to find that 3.07. But as you get into the later 70s , more ratios were available. In the 80s, up to 87, you can find super low number ratios in the 2.5 range but these have a new center housing casting to make room for the huge pinion.

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Thanx everybody for your help

 

I've installed 55/59 lug rear axles under 47/54 trucks a few times and it is pretty simple. It isn't a direct bolt in as you have to move the spring pads and then drill holes on the pads 1-3/4 inches to the front side from the old hole to center the wheels in the wheel wells. Back in the 60's and early 70's it was a very common thing to do when either going to a V8 or going to an open drive transmission.
Most of the 60's Chevy pickup rear axles were coil spring and have big ugly brackets for the sway bar welded or cast in that keep them from being a good swap and as mentioned earlier in the late 60's the rear axles got wider.

 

nope. The cars had an oval shaped center section, trucks are round.

 

Follow on question, will car axles fit the truck housing to convert to 5 lug?

 

No.

 

not with car...like was just said, but some of these GM 1/2 ton rears can be swapped from 5 to 6 or vice versa, if you get the correct donor years of shafts.

I don't know exactly when there was a major change in the 70s or 80s, when the newer style axle shaft would no longer fit the preceding year. I think spline change or???

but as an example: If you bought a 70 C-10 which was the first year of the wider rear, and last year of 2wd 6 lugs, and you wanted to switch to 5 lugs without changing the entire rear, then you could swap in the 71-up shafts from the new 5 lug 2wd axles that came out in 71.

But, there is a cut off date where something was changed, so I guess you'd need a Hollanders or GM parts book to find out what will fit.

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Alot of good information thank you guys. So if i was to use a rear end from a 55-59 would i use the same driveshaft from the same year just get it fitted and change the yoke on the transmission side?

 

If interested there is a ver group on Facebook covering Chevrolet & GMC advanced design trucks. Very good source for tech questions and ideas.

 

whats it under?

 

Also do a search for Chevy truck forum. I think it's listed as a '67-'72 forum but they cover from '47 to present with sections of different designs such as the Task Force. A lot of info there.

 

Look up the AD Trucker forum, for tons of info on these trucks.