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Discussion Starter #1
I have a 39000 mile lmm sitting on a pallet in the garage out of a wrecked truck. I have been looking for a truck wth a blown motor to put it in. I found a lly with one but can I use the lmm in the truck. I know it’ll bolt in but what will need to be done. I would have both complete trucks and harnesses. What about using the 6 speed instead of the 5 speed Allison?
 

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two options

1: Put the LLY reluctor wheel, cam sensor, crank sensor in the LMM along with LLY injectors & harness and run it as an LLY

2: Find an LBZ ECM/TCM, Harness (Eng and body side), throttle petal, cluster and run the LMM as an LBZ in the LLY truck with the six speed.
 

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two options

1: Put the LLY reluctor wheel, cam sensor, crank sensor in the LMM along with LLY injectors & harness and run it as an LLY

2: Find an LBZ ECM/TCM, Harness (Eng and body side), throttle petal, cluster and run the LMM as an LBZ in the LLY truck with the six speed.
I vote option #2:thumb::thumb:
 

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Discussion Starter #4
Option 2 would be the only way I’d do all that to make it happen may just keep looking.
 

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If you go option #2, I have a write up I did years ago on this site somewhere called "LB7 to LBZ wiring how to" Think its under my RPM Motorsports user name
 

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Discussion Starter #6
I did a quick read on that and it doesn’t look as bad as I thought. I did find a lbz with a broken crank at a Chevy dealer in Kentucky on line last night. I’m assuming that would be an easier swap? Is it common for the duramax to break cranks? Seems like I’ve seen quite a few while I’ve been looking.
 

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broken cranks happen from time to time. No real good explanation? The ones I have seen in person (2) were both hopped up coal rollers:shake::shake:

I have read where stock ones break as well

doesn't seem to be a good solid commonality in this.

Its not super common or some type of epidemic


I would not be scared to buy it and move forward. :2cents::2cents:
 

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I did a quick read on that and it doesn’t look as bad as I thought. I did find a lbz with a broken crank at a Chevy dealer in Kentucky on line last night. I’m assuming that would be an easier swap? Is it common for the duramax to break cranks? Seems like I’ve seen quite a few while I’ve been looking.
We've repaired bone stock trucks that have broken cranks cruising down the highway, and we've abused stock cranks at over 1450hp without issue. like stated above, its a crap shoot but not as common as the net makes it seem.
 

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Discussion Starter #9
If I use the electronics out of the 07 lbz truck is the lmm pretty much a direct swap in?
 

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If I use the electronics out of the 07 lbz truck is the lmm pretty much a direct swap in?
Yes. You will need both the LBZ engine harness and the body side engine harness. re pin a few wires, add a couple and away you go. If you use the LBZ fuse box, you don't need to move the paired orange TCM power wires. Ditch the LMM EGR setup, use the LBZ if needed for emissions
 

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Discussion Starter #11
Ok but what I was asking is I found an 07 lbz truck now with a broken crank. If I drop it into this truck is it essentially a direct plug and play?
 

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Discussion Starter #12
The complete vehicle harness I have from the lmm I am parting, does that have everything I need to convert the lly harness? Or do I need the lbz harness in order to have the correct connections.
 

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Ok but what I was asking is I found an 07 lbz truck now with a broken crank. If I drop it into this truck is it essentially a direct plug and play?
If you use the LBZ harness yes direct swap. You will need to swap the EGR setup from the LBZ or forget to put it on.

The complete vehicle harness I have from the lmm I am parting, does that have everything I need to convert the lly harness? Or do I need the lbz harness in order to have the correct connections.
You need the LBZ harness, huge change from LLY/LBZ to LMM harness
 
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