Rear end swap?

[86c10]

My truck currently has a 2.73 10 bolt and I have a 3.73 12bolt sitting around and was wondering if there is any way to figure out what might happen to my mileage if I switch. I'm getting about 15 mpg now with a stock 305/350 and the 2.73. Most of the roads where I use the truck are 55-65mph, not much intown starting and stopping.

[pholliday1]

It's gonna get worse..........LOL you knew that already, My guess is about 2mpg. But look at the good side the truck will feel like you have 35-50 more hp.

[gildardo01]

you wont need a first gear anymore...

[bake74]

It's gonna get worse..........LOL you knew that already, My guess is about 2mpg. But look at the good side the truck will feel like you have 35-50 more hp.

X2

[86c10]

It's gonna get worse..........LOL you knew that already, My guess is about 2mpg. But look at the good side the truck will feel like you have 35-50 more hp.

Yeah unfortunately I thought that it would get worse, but like you said it will feel like it has more power. I can probably live with 2 mpg less, the truck just gets used to run to Lowe' and Homedepot.
Thanks

[86c10]

Will the stock drive shaft be the right length?

[Jason S]

You should be able to use the stock driveshaft if your just swapping 10 to 12 bolt.

[Captkaos]

You will need a hybrid u-joint though...

[86c10]

You will need a hybrid u-joint though...

Will a parts guy know what I'm talking about If I tell him what I'm doing? Or do I need to ask for a specific part number?

[Captkaos]

He should know what you want unless they are under the age of 25.,..

[bake74]

     If your 10 bolt is the standard 1310 u joint series and the 12 bolt is the standard larger 1330 series this is what you can use.   http://www.summitracing.com/parts/PCN-253/

     This web site will give you measurements of each side so you can measure them and double check that this one will work.

[Dave C.]

Don't you need to change the rear wheels as well?  I thought that only the 4wd models had the 12 bolt.

[Captkaos]

every thing prior to 1981 used 12 bolts, everything after used 10 bolts (an yes there are exceptions as they were using up the remaining 12's)

[86c10]

     If your 10 bolt is the standard 1310 u joint series and the 12 bolt is the standard larger 1330 series this is what you can use.   http://www.summitracing.com/parts/PCN-253/

Thanks, bake I will look into that when I get closer to the swap. I'll have to wait on better weather, I'm working outside in the drive way.

He should know what you want unless they are under the age of 25.,..

That helps, now I know who to stay away from.

Don't you need to change the rear wheels as well?  I thought that only the 4wd models had the 12 bolt.

As far as I know the 12 bolts came as 5 lug 2wd and 6 lug 4wd, and the axle shafts will change from one housing to the other. I'm sure somebody will chime in if I'm wrong.

every thing prior to 1981 used 12 bolts, everything after used 10 bolts (an yes there are exceptions as they were using up the remaining 12's)

That explains my '83 that I parted out. Was 3.73 a factory option in the 1/2 ton trucks?

[thirsty]

I had a K10 with 2.73 once. I had plenty of motor in that truck so I could somewhat live with it. I used the truck for a daily driver. I wheeled a lot then but never took that truck off road other than hunting or work. I put some new all terrain type 33's on it and got to say that I got pretty decent mileage and it was one of the best short wheel base trucks that I ever drove in the snow. I didn't have that rust bucket long then went back to driving my wheeling rigs year round and suffering in the snow.