K10 newbe

[ALEXEP]

Good day to all. My name is Alex and I'm new to the square body world and I need some advice on LS swap with a 4L80 4x4 in to a 1978 k10. I need to know how to order the adapter to run the newer trany to match the existing stock transfer case. I've done a couple of LS engine swaps but never on a 4x4 configuration. Please let me know where to begin to order the right adapter for the combination I have.

Thanks

Alex

 

[Strick]

Welcome from NC. Have you sourced Advanced Adapters yet? I have used them in the past.

Strickland

 

[ALEXEP]

not yet. What kind of information I need from the truck transfer / Trany before I call them?

 

[ALEXEP]

And thanks for the welcome!!!!

 

[Strick]

not yet. What kind of information I need from the truck transfer / Trany before I call them?

Look for an adapter to use the 4L80 to the NP205 or NP203 case that you're using. You probably can look it up on the interweb. I have one on a TH350 for use on a NP208 aluminum case. GM used this setup for only 2 years (81-82) that I know of, but it's offered by AA. Here's what I found for you with a quick search. Good luck.

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Strickland

 

[ALEXEP]

Strick,

I called Advance Adapters and they said more that likely I have in the truck a tubo 350 or 400 PN I need for the adapter is 50-0411 and cost around $700.00. The only thing he explained to me, is that I will need to take it to the transmission shop to install a gear that the 4x4 version does not come with it, because is mounted in the transfer case and needs it for the communication with the TCM. Have you or anybody had to do this modification? Please let me know.

Thanks,

Alex

 

[Bextreme04]

It depends entirely what you are swapping from. A 78 K10 is likely a TH350/NP203.. which is not going to be easy to convert at all. You will be better off just getting a 4x4 4L80e with the round adapter and then use an 85-later NP208 or passenger drop 241 if you can find one. There are also a bunch of NP 205's that you can get to work, but it can get very complicated very fast. My 1980 K25 was a TH400/NP205 truck stock, so I used a 2wd 4L80e and cut down the output shaft to 4-3/4" and used a Northwest fab adapter plate to convert the index ring from the TH400 size to the 4L80 size

 

[Bextreme04]

Strick,

I called Advance Adapters and they said more that likely I have in the truck a tubo 350 or 400 PN I need for the adapter is 50-0411 and cost around $700.00. The only thing he explained to me, is that I will need to take it to the transmission shop to install a gear that the 4x4 version does not come with it, because is mounted in the transfer case and needs it for the communication with the TCM. Have you or anybody had to do this modification? Please let me know.

Thanks,

Alex

A 97-later 4L80e from a 4x4 will not have a tone ring on the output. All 2wd ones have the tone ring. If you get a NP208 or passenger drop 241, they have kits to add a VSS on the output of the transfer case. Shifting and engine braking can get wonky in 4-lo if you don't have the vss on the transfer case output. You need to figure out what is in the truck right now, in order to figure out what the best course of action is. Running a 203 behind a 6.0/4l80 is a recipe for disaster.

 

[ALEXEP]

Strick,

Thanks for the info!!!!

 

[ALEXEP]

A 97-later 4L80e from a 4x4 will not have a tone ring on the output. All 2wd ones have the tone ring. If you get a NP208 or passenger drop 241, they have kits to add a VSS on the output of the transfer case. Shifting and engine braking can get wonky in 4-lo if you don't have the vss on the transfer case output. You need to figure out what is in the truck right now, in order to figure out what the best course of action is. Running a 203 behind a 6.0/4l80 is a recipe for disaster.

ok let me find out exacly what I have in the old truck.

Thanks for the feedback!!!

 

[ALEXEP]

Let me ask you guys something. Can I just swap the engine and leave the tranny alone? Will the T350 or T400 handle the 6.0 ls engine in case this turns ugly? please let me know your feedback.

Thanks

 

[Bextreme04]

Let me ask you guys something. Can I just swap the engine and leave the tranny alone? Will the T350 or T400 handle the 6.0 ls engine in case this turns ugly? please let me know your feedback.

Thanks

It would be VERY unlikely for your K10 to have a TH400. If it does, everything becomes MUCH easier. Yes, you can retain the stock trans, but you'll need to find a solution for the kickdown cable.

You are going to be doubling the power output through the trans and transfer case with a 6.0l over the stock engine. A TH350/NP203 isn't exactly known for power handling and reliability to begin with. They would probably be fine with a rebuild with power handling upgrades as long as you aren't running big tires.

 

[Kurnacopia]

Welcome from AZ!

Here is a good place to start. I too am using a 4L60e to NP205 in a 78 Scottsdale 4x4. I researched the hell out of this. here is where I started: https://www.advanceadapters.com/adapter-4l80-to-np205

in doing this you have to figure out the spline type on the bolt pattern of the 205. I have a 27 spline with the 8 bolt config.

I have also seen adaptors here:

4x4 4l80E to Figure 8 NP205 Adapting Kit

4x4 4l80E to Figure 8 NP205

www.offroaddesign.com

this may not be exact to what you need for your 205 but it should get ya started. Also, figure out if you want to twin stick that 205:

NP-205 GM style Stainless Steel Twin-stick Shifter W/boot P/N NP205GM

NP-205 GM style Stainless Steel Twin-stick Shifter

jb-custom-fabrication.myshopify.com

its easy enough to do and makes that 205 really work and its really cool too

Best of luck my friend!

 

[ALEXEP]

It would be VERY unlikely for your K10 to have a TH400. If it does, everything becomes MUCH easier. Yes, you can retain the stock trans, but you'll need to find a solution for the kickdown cable.

You are going to be doubling the power output through the trans and transfer case with a 6.0l over the stock engine. A TH350/NP203 isn't exactly known for power handling and reliability to begin with. They would probably be fine with a rebuild with power handling upgrades as long as you aren't running big tires.

thanks Eric!!!!!

 

[ALEXEP]

Welcome from AZ!

Here is a good place to start. I too am using a 4L60e to NP205 in a 78 Scottsdale 4x4. I researched the hell out of this. here is where I started: https://www.advanceadapters.com/adapter-4l80-to-np205

in doing this you have to figure out the spline type on the bolt pattern of the 205. I have a 27 spline with the 8 bolt config.

I have also seen adaptors here:

4x4 4l80E to Figure 8 NP205 Adapting Kit

4x4 4l80E to Figure 8 NP205

www.offroaddesign.com

this may not be exact to what you need for your 205 but it should get ya started. Also, figure out if you want to twin stick that 205:

NP-205 GM style Stainless Steel Twin-stick Shifter W/boot P/N NP205GM

NP-205 GM style Stainless Steel Twin-stick Shifter

jb-custom-fabrication.myshopify.com

its easy enough to do and makes that 205 really work and its really cool too

Best of luck my friend!

Thank you Mike. I'll call them in the morning.