Are 2.73 gears hard to find?

[Ardenq]

Hey guys, poked around the site and finally registered to get some info I couldn’t find searching.

I have a 68 c10 with 250 and 3 speed and an open, I’m told they came with 3.73 gears but I’m not sure (they’re likely stock based on the rest of the truck).

I’m looking for a high gear set for a big block swap but 3.08 is the best I could find.

It looks likely they made a series 2 carrier, is that hard to find? I couldn’t find any info for 67-72 trucks.

If I have a series 3 I “should” be able to run a used set of 2.73 gears. Are they only square body c10’s?
A used set of gears and a series 3 posi and I should be all set?

After looking through craigslist, the classifieds and eBay I didn’t see a lot of options, are they in demand, or is it one of those things guys don’t really sell because there isn’t a market?

Going with big block/auto and want to keep the trans I have.

Thanks for any info,
Arden

[Mike C]

They were really only late 70’s. Early 80’s when they switched to the 10 bolt you get 2.41 or 2.56 gears.

I just sold a ‘78 Blazer that had 2.73 gears in it. They are not common and NOT in demand!

[Warrens69GMC]

I have a 350/th350/3.08/28" tires and I can't see going to 2.73 gears even with 27" tires.
I can do 90 down the freeway without the engine screaming.

Just grab a 3.07 readily available rear axle and be done.

[Mike C]

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[Ardenq]

Yeah I’m in Austin, I appreciate the offer but I’m going to hold out a little bit and try to find a set of 2.73’s. Do you know if my six cylinder three on the tree should have a series three carrier?

Originally Posted by Mike C

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Posted via Mobile Device

[HO455]

Originally Posted by Ardenq

Yeah I’m in Austin, I appreciate the offer but I’m going to hold out a little bit and try to find a set of 2.73’s. Do you know if my six cylinder three on the tree should have a series three carrier?



Posted via Mobile Device

If you have an unaltered 3:73 rear end you don't have a 3 series carrier. I believe that 3:73 is standard with 3:07 and 4:11 being the only options. You can check your SPID to see what may have been ordered. But the only way to be sure is to remove the cover. It is possible your truck had a failure in the past and a 3 series carrier was installed with a thick 3:73 ring gear, or a 3:73 ring gear with a spacer. But once again removing the cover is the only way to know. Its an easy job and inexpensive to boot.
GM is pretty smart so there was a reason they didn't offer 2:73's with the stock power trains. Are you running significantly shorter wheels and tires than stock? Remember that when you install taller gears that the load on the engine is increased and it has to work harder to do the same work. If you are trying to gain fuel economy you may end up burning more fuel as the engine will not be running in its most efficient power band. Keeping the 3:73's and getting an overdrive is more expensive but may be better in the long run. Just my opinion and by no means the last word on the subject.

[Mike C]

The carrier break for a truck is 2.73 and down. The 3 series is 2.76 to 3.42 and the 4 series is 3.73 and up. So if you have 3.73 you have the 4 series carrier. If you want to run the 2.73 you will need a 2 series carrier. If you can find the 2.76 you can run a 3 series carrier.

The Blazer I just flipped was actually 2.76 geared. It was a 4x4 78 originally TH350/NP203 with a 400 small block.

Originally Posted by Ardenq

Yeah I’m in Austin, I appreciate the offer but I’m going to hold out a little bit and try to find a set of 2.73’s. Do you know if my six cylinder three on the tree should have a series three carrier?



Posted via Mobile Device

[Bigdav160]

I think there was someone in the driveline area was asking about swapping 3.73 for their 2.73 and limited slip

[jamie72]

had a stock 88 1/2 ton with 2.73 it was a 12 bolt rear, maybe look for one of them as a donor