New bolt in rear end, question

[ncsurveyor]

This is my first post guys. I bought a 68 C10s back in February that I’m making plans to restore. I’m considering buying a new bolt in rear end, for one reason, just to have a new, clean entire rear end setup, and two because I’m not very mechanically inclined and I’m still learning about working on my truck and I wouldn’t know where to start as far as rebuilding. Does anyone have any experience with a full bolt in rear end? Here’s the one I’m looking at. How do I figure out what length I need? It comes in 56”, 58”, and 60”. Don’t flame me too bad if this is a stupid question, I’m trying to learn.
https://www.speedwaymotors.com/Fabri...In,383371.html

Also, what gear ratio would you recommend? I’m planning an ls swap, not sure what size yet, probably a 5.3 or 5.7. And I’m considering keeping the 3ot or maybe switching to an automatic.

[RustyPile]

That rear end is not a "bolt-in" unit.. Some fabrication is required along with modifying the driveshaft.. Unless you plan to do some serious drag racing with a high output engine, and highly modified chassis, that Ford fabricated 9 inch would be a last choice..

Several factors are involved in selecting gear ratios.. Transmission type and power band of the engine you install are the most important factors.. Driving style and speed ranges are also considerations. A ratio somewhere ranging between 2.43 to 4.11.. In other words, you need to supply a lot more information before proper advice can be given..

How about telling us more about your truck.. You may find that the best approach toward learning about these old trucks is to repair, refurbish, and just generally recondition what you have before tackling a "full blown" restoration..

[truckster]

Lenoir, huh? I have family near there. I plan to visit the end of next month if this coronavirus dies down.

Anyway, my recommendation would be to find a rear end shop that can take what you have and make it what you want. That one you linked to would definitely not be a bolt-in deal.

[Richard2112]

If you're planning to build your truck I suggest planning out your entire drive system fully. That is determine the use of the truck first. Is it towing/hauling, is it a grocery getter, is it a street racer, is it a rock crawler is it a quarter mile machine....Each answer has a different optimum setup. other considerations are economy, performance, longevity, comfort, drivability...How frequently are you willing to tune it, repair it, or modify it. Tire size, for example will have an effect on gear ratio, not only at the differential but also at the transmission.

If you're planning on some highway miles with a little economy, a transmission with overdrive might be in the cards. It would be helpful to predetermine what that transmission ratio and tire size might be and then determine which ring and pinion setup would be a good match for the intended purpose. When you have determined your purpose for the truck, settled on the transmission for that purpose, the tire diameter and differential ratio, then you know what rpm range you'll spend most of your time in.

When it's time to build your motor, build it with that target goal in mind. That is if you decide that you want to do 70 mph on the highway frequently, in fifth gear, and would like to be able to pass up a gas station occasionally, then you may want to build for low rpm, high torque so fifth gear is actually usable.

The bigger your tires, the higher your rpm will be, the lower your gearing, the higher your rpm will be...you'll want to think about the whole system. Where do you need the motor to make power. What rpm range are you targeting and at what speed do you want that rpm range to develop.

[ncsurveyor]

Thanks for the suggestions guys, looks like I’ve got more planning to do. My first goal for now is to convert it to 5 bolt and lower it a little with some nicer wheels. It drives great now and I’m enjoying driving it. I’d like to do this to it until I can sell a vette and fund a new motor. How hard is it to change the axles out in the rear end?

[ncsurveyor]

Thanks for the suggestions guys, looks like I’ve got more planning to do. My first goal for now is to convert it to 5 bolt and lower it a little with some nicer wheels. It drives great now and I’m enjoying driving it. I’d like to do this to it until I can sell a vette and fund a new motor. How hard is it to change the axles out in the rear end?

[truckster]

It's actually pretty easy. You'll want to change the outer bearings and seals at the same time.

First jack up the rear and remove the wheels and drums. Remove the rear cover (make sure you have a pan under it). Rotate the wheel until you can get to the bolt holding the retainer pin. Remove the bolt and the pin should slide out. You don't want to move the spider gears with the pin out, because they'll fall out. If you do, don't worry; it's not that hard to get them back in. Now push in on the axle flange and the C-clip will fall off the inner end of the axle. Repeat on the other side. Replace components in the opposite order.

[Mike C]

Good advice in this thread. One of the best things you can do is read about other people's efforts. LOTS of questions like yours. Use the search box at the top of the page and select the button 67-72chevytrucks.com to search this site.

[gmc684x4]

Make sure you use heat on that little bolt its usually locktited in and be a bear to remove once the head of the pinion bolt breaks off and it is a small bolt

I use a hand held propane torch to heat it up good and hot and replace it with a new bolt on reassembly for good measure

Several places make 5 bolt axles to fit your diff not sure if 73 and up axles will be a direct bolt in

[HO455]

You could drop your truck off at a shop and have them go through your entire rear end and give you the ratio you desire for about the same money as that one from Speedway. That is what I did with my Burban. It was already 5 lugs, but the carrier was breaking apart and needed replacement and one axle ended up being junk. I was out the door for $1550 with a rebuilt used posi carrier with new 3.73 gears and all new bearings and seals, installed in the truck. Done at 6 States here in Portland OR.