Antonio--
The 3.73 and 3.07 gears use different differential carriers, the reason
is to space the ring gear to the proper position for the different size
pinion gears used. So, you need a 3.07 carrier, which you may be able
to buy from Chevy for $$$ or you may be able to find one used for a more
reasonable price. It would have to be from a truck or van 12 bolt rear,
probably from the 70s. I bought a used complete van rearend for $75
that had the 3.07 gears and carrier that I used...plus I had to buy new
bearings and seals and crush sleeve, which added close to $200 to the
cost of the project. You also need to know what you're doing to set up
the ring and pinion gears, the pinion depth and backlash as well as
bearing preload are all critical, and take some equipment and knowledge
to get right. The facory shop manual for any 60s or 70s truck should
have the info you need, if you can find such a manual. Or, find a good
rearend shop that will do it for you, figure about $200 labor...and they
may have a used carrier for sale also, possibly the gears also (from
someone who replaced the 3.07s in his 4x4 with 3.73s for better
towing/acceleration).
Jim F
59s in AZ
"Antonio R. Tijerino" wrote:
>
> I installed a '65 Chevy truck rear end on my '53, and you are right it is a
> 3.73 ratio, but it fits just perfectly after removing the coil spring
> perches and putting new saddles for the leaf springs. Mine were already
> converted when I got it. BTW: it has six lugs and the original wheel fit
> perfectly.
> My question is: Can I change the ratio to something like 3:03 just by buying
> one of the kits from a Jegs catalog? How hard is it?
> The kits seem affordable, but what other expenses are involved if you do it
> yourself?
>
> Thanks,
>
> Antonio
> '53 3100
>
> -----Original Message-----
> From: owner-oletrucks@autox.team.net
> [mailto:owner-oletrucks@autox.team.net]On Behalf Of J Forbes
> Sent: Friday, May 18, 2001 7:44 AM
> To: Old Trucks List
> Subject: [oletrucks] Rearend Questions--later truck rears
>
> Hi...
>
> The price of $125 for a 70s-80s 4x4 rearend is really cheap...around
> here they bring about $400 these days.
>
> The 64-69 truck rearends are about 61" wide, like the 50s truck stock
> rearend, plus they are 6 lug. The most common ratio is 3.73, which is a
> bit much, but does allow highway crusing around 60-65 mph.
>
> The 70-87 (-91 Blazer, Suburban also) full size truck rearends are about
> 63" wide, and are 5 lug on 2wd trucks, and 6 lug on 4x4s (70 2wd are
> also 6 lug). Common ratios include 3.07, 3.40, and 3.73.
>
> You can use the gears and carrier from a 70s truck or van 12 bolt
> rearend in a 60s rearend, to get 3.07 gears with the narrow
> housing/axles. I did this in my 66 Suburban, it worked out great, with
> big block power.
>
> Jim Forbes
> 59s in AZ
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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