1968 C10 Ring and Pinion Swap Cost

[RustyandGreen]

Hello,

I was thinking of changing the gears in my 12 bolt. I called a local rear end shop and told him I have 3.73s non posi but I'd like to go with 3.08s. It seems a different case is needed but he can get them used so with the new ring and pinion, bearings, and seals it would be $1000 out the door. Is this a fair price? I have a 250cid and 3 speed manual but it feels topped out at 50-55mph. I've taken it to 60 a couple of times but I'm not that comfortable with all the noise coming from under the hood, and I do need to take it on the freeway. I don't tow anything and occasionally haul an engine or something but nothing really heavy. On an off topic note, I inquired about changing the ring and pinion in a Ford 9 inch and was also quoted 1K even. Maybe that's the standard today? I'm in Northern California just outside the Bay Area.

[RustyandGreen]

I forgot to add a photo of the markings on the rear axle, it reads HA 1213K. I think HA means 3.73 non posi, anyone know what the rest means?

[demian5]

If the carrier has to come out then rule of thumb is a grand. Best thing i did was 3:07 (truck gears - 3:08 is car).

[RustyandGreen]

I see, I guess it's a fair price then. I really want to see the difference with 3.07 or 3.08 gears on the highway...

[jimijam00]

If you haven't driven a truck with that engine, trans, and gear combo, I recommend you do so since $1K is a lot to drop if you don't like it.

[RustyandGreen]

Good point, not easy to find though. It does seem to be the easiest way to get a better performing truck for freeway driving.

[Jason Banks]

I also have a 250 3ott truck but I have factory 4.10 rear gearing. 70 is about TOP speed on the highway. But it almost wheelies away from stop lights. Mine is currently howling. I had an estimate for $900 but I already have some of the parts. I think it is a great point to see what that's going to drive like before taking the leap. I was actually going to go to a 3.73 gearing.

The truck pictured in my signature was a 402 with 3ott and 3.08 rear gearing(factory posi). I remember it being a good highway cruiser. I actually used to drive it about 600 miles round trip every week. This was about 20 years ago though. The stock rebuilt 402 easily had 100 horsepower on the 250 though.

[uncle]

Why not just buy another rear axle that already has 3:08 gears? Way cheaper than a grand.

[RustyandGreen]

I don't know anyone with a C10 with that exact combination, most people I know have newer trucks and certainly no 250s! I haven't heard anything really bad yet about those gears though.
A complete swap would save money if it doesn't need any work, which is also a bit of a gamble. I'd like to start driving the truck regularly so new bearings and seals sounds good as well. If I get it done I'll come back and update on the results. I appreciate all the comments and suggestions.

[geezer#99]

Here’s an easy test.
Drive at 48 mph. With your gearing of 3.73 that will be about 2200 rpm.
See how that sounds and feels for power.
That’ll give you a feel for what the gear change will do.

[RustyandGreen]

I'll hook up a tach and try it. I drove my 1966 f100 today, it has 3.50 non posi 3 speed man. and 352cid. It does 65 at 2600 rpms, I liked it. I'll try that with the chevy and get back to you. You think it will be 2200 rpms at what speed with the 3.08 gears?

[geezer#99]

That would be the rpm at 60 with the 3.07 gears.
I’m assuming a 28 inch tall tire.
I like this calculator.

http://www.advanced-ev.com/Calculators/TireSize/

[BCOWANWHEELS]

3.07 , 6 cly is going to be a real dog,forget hauing or pulling a traier also.theres a reason gm put 3.73,s

[RustyandGreen]

Well, on the freeway it's already a dog. It will be slower to accelerate but it's a tradeoff, is it better to accelerate quickly and hit a brick wall at 55, or accelerate slower and cruise at 70? There seems to be people that have made the swap and are very happy with it. I suppose a 5 speed would solve everything but I'm not ready for that yet. I don't tow anything, even as it is I couldn't imagine towing something with a stock C10, the brakes are barely adequate for stopping itself, a couple thousand pounds behind it would make me nervous!

[BCOWANWHEELS]

Well do it then and quit talking. You,ll see 4 yourself

[RustyandGreen]

Okay, but may I do the tach test and reply to Geezer#99 before I quit talking?

[leddzepp]

You’ll be much much happier with 3.07’s. There’s a reason GM used those too

[Jason Banks]

Keep talking rustyandgreen. I don't understand the reasoning to be so rude.

[3767]

Former poster is right. Lower gears are what GM used to get the 6 cyl going. Especially if u were pulling something. U said u were not ready for a 5 speed yet. If u have plans 4 that, then u really need to think this over. U change and yes a grand at minimum is coming out of your pocket. U get a 5 speed...u gotta change back to your current gear or go lower depending on tire height and tranny gears. The only way u get to keep those 3:07's and get a 5 speed is to go to a richmond tranny.

[factorystock]

Chevy left a lot to be desired as far as 1/2 ton ratios from '67-72. Namely, no intermediate ratio between 3.07 and 3.73. The 3.40 finally came on in the square door years, which IMO, would be perfect. You don't want to go to drastic in ratio changes. Good performance depends on power of engine, weight of vehicle, terrain, as well as axle ratio

[3767]

This is where a 5 or 6 speed could really help u out. Low first gear to get u moving and od 2 help keep rpm down 4 fuel savings.