Rear D44, Car 10 bolts, and Ford 9 inch rear differentials

[AuroraGirl]

So Im putting together my to do list for my 78 and I have some questions as I have options. It currently has a stock 12 bolt in the 6 lug rear and from what i gather the 12 bolt in trucks wasnt that good? I also have a secondary 12 bolt truck rear under a trailer

I have 3 cars with 10 bolt rears i could salvage.. but they probably differ from the trucks? one of the cars may have a car 12 bolt but I think its 10 from what I can see. Hard to tell.
I also have a ford 9 inch(and 8 inch but i wouldnt even use that)
I also have a D44 rear axle(truck has a front D44, i could have matching twins!!!!!!!!)

Im wondering which is the best rear diff option for a half ton truck.

 

[bucket]

Of all those ones, the one already under the truck is the best one. The 9" should be the strongest of the bunch, but in stock form, not worth the trouble of the swap.

 

[78C10BigTen]

Of all those ones, the one already under the truck is the best one. The 9" should be the strongest of the bunch, but in stock form, not worth the trouble of the swap.

I hate ford swaps into chevys!! Ok its strong, BUT i bet theres a better gm option instead.

 

[Vbb199]

I hate ford swaps into chevys!! Ok its strong, BUT i bet theres a better gm option instead.

Except in the case of a dana 60.
Its FOR ford, but not made by ford
Weirdly tho, the ford d60 has weaker knuckles than a chevy 60?

 

[Vbb199]

And i thought the truck 12 bolt was ****? Truck 10 bolt better?


But car 12 bolt is better than car 10 bolt?


Ive never compared them, so i dunno.
But the car guys always go for the car 12 bolt vs the car 10 bolt


And every billybob says the truck 12 bolt is garbage

 

[Grit dog]

There are many more actual real world practical or limiting considerations that need to be considered before what axle, in theory, is “good.”
Axle width
Bolt pattern/axle shaft swap cars 5 bolt, right? And how it relates to axle width, # of splines and axles shaft diameter.
Gear ratio, are they the same? Or does it matter?
Shock and spring mount location and type. Cutting and welding.
Brakes car vs truck
U joint size
Driveshaft modification due to different length diff carrier.

And then, if the other axles are actually in good order or what it will take to get them in order, compared to what’s already under the truck. After determining how much cost and work it will take to make a particular axle “fit”

These considerations need to be addressed with your donor axles before determining if it’s better to swap it out.

 

[AuroraGirl]

Beings its a 12 bolt with a G80 option, I dont think I will want to keep it. But a square body 10 bolt can be had for decent money on FB. OR would a car 12 bolt be a better source to maybe change mounting pad points on? I plan for decently heavy duty use of the truck but im not gonna move a mountain with it. Maybe keeping the 12 bolt until it starts to show wear/need to replace is a good option?

 

[bucket]

I wouldn't go to the trouble of swapping a truck 12 bolt for a car/truck 10 bolt (8.5" ring gear) unless I killed the 12 bolt and had a 10 bolt sitting around and ready to go in.

The Chevrolet car 10/12 bolt thing is generally just through 1971. The 12 bolt was much stronger and tended to be found in cars over 300 hp. The 10 bolt in those years was weaker and had a 8.2" ring gear. Starting in '71, 8.5" 10-bolt came along and was generally used in all cars that would have previously had a 10/12 option.

The car style 12 bolt is comparatively rare, desirable and expensive too. Prices for them are along the lines of a front Dana 60 that everyone searches for. $500 for a builder, all the way up to $1500+.

 

[Vbb199]

I wouldn't go to the trouble of swapping a truck 12 bolt for a car/truck 10 bolt (8.5" ring gear) unless I killed the 12 bolt and had a 10 bolt sitting around and ready to go in.

The Chevrolet car 10/12 bolt thing is generally just through 1971. The 12 bolt was much stronger and tended to be found in cars over 300 hp. The 10 bolt in those years was weaker and had a 8.2" ring gear. Starting in '71, 8.5" 10-bolt came along and was generally used in all cars that would have previously had a 10/12 option.

The car style 12 bolt is comparatively rare, desirable and expensive too. Prices for them are along the lines of a front Dana 60 that everyone searches for. $500 for a builder, all the way up to $1500+.

No kidding.
My dad preached to me about the 12b in his 72 poncho in regards to the price.... i had no idea they were so pricey.

 

[78C10BigTen]

No kidding.
My dad preached to me about the 12b in his 72 poncho in regards to the price.... i had no idea they were so pricey.

Im curious now... my dad has (had... hes dead) a 71 ponty GP. Wonder whats under that???

 

[rpcraft]

If you have no problems with the 12 bolt stick with it. If you blow up the g80, which is common, and really want something beefier, you would be best off swapping to a 14 bolt semi floater. It can be found with 6 lug axles, can also come with your gears of choice, and also locker choices similar to the g80 type unit, but that's still the weak link. It won't be a bolt in for a k5 so depending on what your rig is it may require cutting off the old shock mounts and spring perches and relocating them, but it is a solid upgrade if you can find one, and it doesn't hurt your ground clearance as much, like swapping to a 14bff would. Alternatively you could swap to a 10 bolt from a model similar to your rig and it should be a direct bolt in and according to the numbers cruncher types it is technically beefier, but only up to about 31 inch tires and stock power levels. If you start running more power and bigger tires the spider gears and axle shafts get explody. Upside is truck 10 bolt parts are a dime a dozen and if you find the right one from modern stuff you can even have your disc brake cake and eat it too.

 

[Craig Nedrow]

Aurora girl, answered this earlier...
Hey Hunter you live in my neck of the woods, and welcome. I installed a lunchbox locker in my 14 bolt, Yukon, and detail it on my build page. Blew up the TH350 with the 454, but the rear end is great. I was wondering what year your truck was, as my 73 K10 has a posi 12 bolt rear and ten bolt front. If you would like welcome to come look at my stuff, look at the thread, gain some knowledge, and make a informed decision. The truck 12 bolt has the small pinion support bearing, so not as strong as the car 12 bolt. However, this truck has NEVER had a problem with the rearend, (stock posi) has probably 100,000 off road miles, hauled many ridiculously overloaded loads, puller a hay trailer consistently with 8000+ still going. The 14 bolt is much better choice if you want to haul heavy loads IN THE BED, as it is a full floater, (ff). I just looked on marketplace, and craigs list, lots of complete, or parting out's there reasonable.


https://www.gmsquarebody.com/threads/1973-k20-350-to-454-swap.29840/

Not my thought, but my experience. You push snow I gather (got any?), so the 12 bolt should be fine, I agree with several posts already here, stay with what you have, as swaps are time consuming, can be $$$. Sure can be done, but relocating pads, getting good penetration on the welds, warping axle tubes, setting pinion angle, special tools Ugg. The only up side is you learn lots, which is good.