The Stovebolt Site Forums The Shop Area Driveline Rear End 1953 3100

Moving forward on a T-5 Transmission conversion and seeking advice on getting an open driveline compatible rear end. I`ve kind of narrowed it down to either a 2004 Chevy Colorado which is 6 lug or a 57 Chevy 3106 truck rear end which I believe I could just swap out the pumpkin and utilize what I have. If this is correct I can get the 57 rear end by driving a couple hundred miles or the Colorado which is available locally. I have the new tranny already and understand a Chevy Astro driveline may be compatible. Cost is $375 for the Colorado rear and $150 for the 57 truck axle complete. Unsure of the gearing in the 57 rear and I know the Colorado is a 373 ratio. Any thoughts,comment or advice greatly appreciated...

According to the GM Heritage Center 1957 Chevrolet Truck Data PDF the 3106 (Suburban Carryall) was either equipped with a standard 3.90 ratio gear set, or an optional 4.11 ratio gear set.

The difference can be noted by checking the passenger side differential pumpkin casting where the ID info is stamped. The standard 3.90 ratio unit ID stamping will begin with the letters "AF". The optional 4.11 ratio unit ID stamping will begin with the letters "AG".

As far as which ratio rear axle will work best with your engine and T5 transmission, that depends on both the engine being used and the T5's OD ratio. More details needed please.

If you choose to use the stovebolt open driveline center section, you'll also need to figure out a way to lock the pivoting spring mounts from the torque tube axle housing at the proper pinion angle. Some people have tried to weld them, bit since there's a rubber bushing involved, that's a difficult procedure. It's simpler to remove the pivoting mounts and replace them with a rigid unit welded to the axle tubes. Those spring mounts are available online from places like JEGS, Racer's Wholesale, etc.
Jerry

>72 overdrive with a rebuilt 62 chevy 235 motor and 235-85-16 tires thanks .

3.73 ratio might or might not work as well as you hope. The main thing is to determine what ratio chain you have in your T5. If first gear is 4.03 (as many did) I would suggest avoiding 3.73 and definitely avoiding the 3.90 or above. 3.73 will make your overall ratio a shade over 15. Your truck was engineered to have a 12.08 overall ratio in first. It was designed so it could haul up to 1000 pounds adequately. A ratio of 15 will mean you'll get about halfway through a city intersection before needing to shift to 2nd. The other common first gear T5 ratio will be 3.76 and that will make your first gear overall ratio a bit more than 14. Better, but the closer to 11.5 or 12 you can get, the more enjoyable it will be to drive.

As for your 5th gear ratio, if you have the .72 or .73 fifth ratio in the T5, then the overall fifth gear ratio with the 3.73 will be okay. It will pretty much mirror the overall ratio you'd have with a 3 speed with overdrive...2.66 or so and that will save you some gas money.

However, if you can find a t5 with the 4.03 first to .86 fifth gear ratio chain and a 3.07 or 3.08 rear end (look for a 12 bolt from the late 1960s) you could be doing well...particularly if you use 15 inch wheels and tires. With those ratios your 1st will be around 12.3 and your final gear ratio will be around 2.64 (around 2.70 with slightly smaller tires). By comparison if you had bought an El Camino with 235 and 3 speed with overdrive, you would have had an overall final gear ratio of 2.73.

Hope this helps.

OK I`m back shopping for a 3rd member to swap in to my existing diff/ rear axle. I understand I need the third member with an open diff to begin completing my T-5 conversion. I`ve located a third member about 200 miles away. The owner says"55-64 pu 3rd all the same besides gearing and all that. The housings all bolt up." Is this correct? I hate to drive that far for the wrong fit. Thanks for the help again...

On my 46 with a 54 fresh 235 I mashed the tranny/ diff ratio numbers apps ad infinitum on which gear ratio to install, falling between the 390 and 411. I’m a glad I went with the 4.11.
Why? My PO had a 3.00 in the truck and I could never use the t5 5th gear, having run that setup informed me of the optimum final drive I wanted but mostly what I learned was besides freeway driving was that 1st and reverse were way tall, especially reverse.
With the 4:11 1st and reverse are in a sweet spot and the clutch takes notably less use on starts, it feels like a truck gearing should instead of a car. 1st is good to get you rolling easily but it is nowhere near a granny gear low, if you are not completely stopped 2nd will pull fine.
As for top speed I can now use 5th on the freeways and 65 is easily doable (I’m typ a 60mph guy at most) and I do not feel I have enough torque to really push anything taller.

Chuck

Swami29 - For the most part that's correct. 1955 1st Series through 1962 (not through '64) 1/2 ton Chevy 3rd member design will bolt into/fit your 1953 rear axle housing. You are correct that there are a number of different gear options over those years, ranging from 3.38 to 1 through 4.11 to 1 depending on the years and regular production vs optional gear ratios.

The 3.90 ratio was standard equipment for all 1/2 tons 1955.1 through 1962. The 4.11 optional ratio was available for 1955.2 through 1957 1/2 tons. The 3.70 ratio was available for 1958-59 1/2 tons. An optional 3.38 ratio was also available for 1959 models, as well as all 1960-62 1/2 tons, when the 3.70 option was eliminated.

The key to knowing what the gear set is in the 3rd member you are interested in comes from the stamped unit serial number, stamped into the passenger side face edge of the housing as shown in the picture below.

If you can get the seller to provide you a picture of the 3rd member housing face on that side, we can help decode what it means and pinpoint the original gear ratio for that unit.

The third member is from a 62 GMC Pickup I assume the Chevy/GMC are the same?

GMC used Dana rear axle in that era. They have an integral carrier, not a 3rd member.
I'm running a D44, 4:10 axle with a power lock carrier
In my 1960 C10.

Swami29 - Do you have pictures of the unit? My early '60s GMC resource info is limited, but in comparing what I have with the Chevy and GMC parts books, the 1960-62 differential carriers should have the casting# "3707340" (GM Part# 3718011) which were used for Chevy and GMC differentials for those years.

This applies to the H033/H035 rear axle assemblies.

Sounds like you found pay dirt if those numbers match.

GMC 1/2 tons were standard H-033 (same as Chevy) 3.90:1 rear axles in 1955-56.

In 1956 an option for Spicer 45 rear axle was available in 3.07:1 and 3.92:1 ratios.

In 1957 only Spicer 45 axles were used and it stayed that way until at least 1959.

In 1960 (the last documentation I have) 1/2 ton GMCs used Spicer 44 rear axles. Available ratios stayed the same.

"Powr-Lok" was available as an option with either ratio in 1958-60.

Spicer 45 and Dana 44 rear axles share many, but not all internal parts. I'm pretty sure that the Dana 44 was just a renamed Spicer 44.

Spicer and Dana are actually made by the same company. The original founder (1904) Clarence Spicer was joined Charles Dana in 1914.

the "Axle code conversion" chat in the 1960 GMC Master Parts Book refers to an "axle code" of H-035 being a Spicer 44 axle.

Thanks for that detailed explanation Bill. As I mentioned I had limited GMC resources to look at in comparing the Chevy vs GMC rear axles. The screenshots below from a 1961 Chevy Master Parts Book and a 1963 GMC Master Parts Book both showed H-033 differentials listed as GM# 3718011 and GM Casting# 3707340 for 1960-62, which is where I drew from for my conclusion above.

I guess what confused me about the GM Master Parts Book is it listed this H033 differential carrier for applications "X" and "Y", which if IIRC stands for 1956 and 1955 respectfully, but also for "J" , which IIRC stands for 1960-62,for the GMC H035 differential.

See my confusion point?

Anyhow, regardless of this info, a picture of the sellers offered differential should help us resolve Swami29's question on if it will fit his axle housing or not.

My GMC Master Parts Book X-161001 revised Dec 1960 refers

to........as
1955.2 ..Y
1956 ....X
1957 ....T
1958-9 ..S
1960-1 ..N

thanks waiting on picture..