85 K20 5.3/4L60 Swap

[Black Beauty]

So I’m finally getting around to swapping my k20. Found what I think is a pretty good deal(unless someone has something else to offer) 05 5.3L w/165k miles with the matching tranny with a 1 year warranty for $2k. I currently have a sbc 350 and a TH400 with the np208. I originally through the 208 and the 4l60 would mate right up and just run it with no issues. However I’ve found that this isn’t the case. Just started this tread to kinda talk through the process as I get it moving and ask any questions that I can’t find the answers to. Any advice before I start is appreciated. Thanks!

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[RoryH19]

Have been through the swap on my K5.
Since you have a k20 with TH400 the spline count would be 30. 4l60e would be 27.
I would recommend a 4l80e trans as this is essentially a TH400 with overdrive.
This way you keep the strength needed for a 3/4 ton.

You will also need an electronic t-case or pulse generator to trigger the computer to shift the trans.
Look for a NP241c from a 90-91 Blazer or suburban. Also take the gauge cluster to have the electric speedo if you go this route.

You will also need an 87 fuel tank and sender for FI.
60 lb fuel pump to fit in the sender too with regulator.

These are the main points I can think of.

You can view my build thread for more details.

 

[Camar068]

You will also need an electronic t-case or pulse generator to trigger the computer to shift the trans.
Look for a NP241c from a 90-91 Blazer or suburban. Also take the gauge cluster to have the electric speedo if you go this route.

you can also put a reluctor wheel on the output shaft at the location of the adapter and drill/tap a hole in the adapter for a sensor.

 

[Crispy]

I think that price is high man, but prices differ regionally. Do you get the PCM, wiring harness, accelerator pedal and TAC module? I think 05 is drive by wire.

 

[RoryH19]

I think that price is high man, but prices differ regionally. Do you get the PCM, wiring harness, accelerator pedal and TAC module? I think 05 is drive by wire.

Good point. I missed the price.
It's a little high for the age, mileage and what it is.

 

[Black Beauty]

I think that price is high man, but prices differ regionally. Do you get the PCM, wiring harness, accelerator pedal and TAC module? I think 05 is drive by wire.

Seemed ok to me for what I’ve seen on the internet. I know ls engines are plentiful but if it has like a hair under 150k miles people think it’s worth it’s weight in gold. Yes, it’s a pull out motor comes with all it needs to plug and play(colloquial speaking)


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[Crispy]

Seemed ok to me for what I’ve seen on the internet. I know ls engines are plentiful but if it has like a hair under 150k miles people think it’s worth it’s weight in gold. Yes, it’s a pull out motor comes with all it needs to plug and play(colloquial speaking)


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Well if its a "drop in" then I say go for it. LKQ, Ebay, and other web stores are the worst place to get an LS. Craigslist GMT800s with blown rear ends or rusted frames for under 1k are the way to go but 2k for a complete job with a warranty isnt terrible. Yea once low mileage comes into the description its gonna cost ya.

 

[HotRodPC]

I agree, that price seems high. It's common to see $800-$1200 around here for Engine, Trans, ECM and wiring harness with 100,000 - $150,000 miles.

 

[Black Beauty]

I agree, that price seems high. It's come to see $800-$1200 around here for Engine, Trans, ECM and wiring harness with 100,000 - $150,000 miles.

Where is “here”? I mean if it makes sense money wise to get it from somewhere else especially if it’s in better shape.


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[HotRodPC]

Where is “here”? I mean if it makes sense money wise to get it from somewhere else especially if it’s in better shape.


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Oklahoma. Where do you live in AZ? I wonder how close you are to a Copart. Sometimes it's even better to buy a complete totalled truck and get all the wiring engine, trans and other parts too all from the same truck, the scrap the body.

https://www.copart.com/vehicleFinde...false,"searchName":"","freeFormSearch":false}

 

[Black Beauty]

I looked into that but I saw you have to deal with auction fees and broker fees and I just saw $$$


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[HotRodPC]

I looked into that but I saw you have to deal with auction fees and broker fees and I just saw $$$


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You do have some auction fees and have to put up a deposit and all that BS. Usually broker fees are if you have someone else do your purchasing for you that already has a Copart purchasing account so you can avoid the BS and putting up a deposit etc. I don't know what trucks are going for these days but sometimes you can get a truck for $600-$800 then $200 in fees and total of $800-$1000 for a complete powertrain and wiring isn't so bad. All depends on availabilty. You go looking in disaster area, like a tornado area and they go cheap for several reason. Plenty to choose from and they are fuct up real good.

 

[Black Beauty]

I looked into that but I saw you have to deal with auction fees and broker fees and I just saw $$$


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[RoryH19]

Of course you will still have the fee to program the ECU and a new harness unless you rework yourself.

 

[Black Beauty]

I was going to send the pcm in to have the vats removed and it tuned to my setup. Got a guy who is going to rewire the whole thing for me. Trading him my carb that’s brand new for the work.


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