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What to do?? W/LS3 Swap

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Mitch711

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Oklahoma
Guys, I need some help with my 89 GMC Jimmy. It is a really nice truck but the motor and transmission have to go.. I have been looking online at motors and transmissions and to be honest it is overwhelming!! I will have to pay someone to do the swap because I am a realist when it comes to my mechanical abilities. I can work on my 350 that's in the truck now but I'm out on the new stuff.. I want this truck to be my daily driver and I will be pulling a boat with it. I plan on keeping this truck I've had 3 others with 350 & 700r4 that I sold over the years. I do understand that this will not be cheap. Below is what I was thinking of doing. Could I get your thoughts on motor & transmission combos. I do not want to cut up the tunnel to make the transmission fit if at all possible. I am only putting a 2" lift on the truck and will run 33's
Crate LS3/6.2L/430 HP W/4WD 4L70E, 4L80E, 6L80E? Which would you run and why? I've made my mind up on the motor but I am not sure on the transmission?

Any thoughts would be greatly appreciated.
 
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LS3/6.2L/430 HP W/4WD 4L80E gets my vote. You will have to run an adapter for the T-Case to keep the passenger side drop. New shafts and such.
Me and a buddy discussed this last night for my 84 K5. If I go this route I will likely go with a 5.3L and Turbo and just do a built 700R4.
 
Mitch711 said:
Guys, I need some help with my 89 GMC Jimmy. It is a really nice truck but the motor and transmission have to go.. I have been looking online at motors and transmissions and to be honest it is overwhelming!! I will have to pay someone to do the swap because I am a realist when it comes to my mechanical abilities. I can work on my 350 that's in the truck now but I'm out on the new stuff.. I want this truck to be my daily driver and I will be pulling a boat with it. I plan on keeping this truck I've had 3 others with 350 & 700r4 that I sold over the years. I do understand that this will not be cheap. Below is what I was thinking of doing. Could I get your thoughts on motor & transmission combos. I do not want to cut up the tunnel to make the transmission fit if at all possible. I am only putting a 2" lift on the truck and will run 33's
Crate LS3/6.2L/430 HP W/4WD 4L70E, 4L80E, 6L80E? Which would you run and why? I've made my mind up on the motor but I am not sure on the transmission?

Any thoughts would be greatly appreciated.
Click to expand...
I'd do the 6l80 if you can. But you have to run a stock computer and it has to be at least a gen IV engine. So 4l80 is easier for sure. But not as good.
Just a few points to research.
JDJ2810 said:
LS3/6.2L/430 HP W/4WD 4L80E gets my vote. You will have to run an adapter for the T-Case to keep the passenger side drop. New shafts and such.
Me and a buddy discussed this last night for my 84 K5. If I go this route I will likely go with a 5.3L and Turbo and just do a built 700R4.
Click to expand...
DO NOT build a 700r4 if your running a turbo 5.3. you will explode it. And end up doing another trans anyway. Do a 4l80 up front and be done.
Stock 5.3 you'd be fine with the 700.
 
Shady, thx for the reply. Why in your opinion is the is the 6L better than the 4L?
I guess I’m looking for the pros and cons of each.
 
6l80 has a lower first gear, a higher OD, and Can take whatever abuse you throw at it in between.
Nothing wrong with a 4l80e either. It's really a great and simple to swap trans.

If your talking crate ls3, then your willing to put money down. And you mentioned the 6l80, So I mentioned the 6l80, which is definitely more money lol.
And more involved. But better.

Best way to do a 6l80 is get a complete 6.2/6l80e combo with computer and harness.
Last I knew there were no aftermarket controllers that work with the 6l80.
 
Nice. When I was researching it they didn't have anything yet.
Good to know they figured it out.
I really want a 6l80 in my tow rig.
I had a 2015 Chevy with the LT 5.3 and a 6l80e combo.
Towed my 9600# trailer through the mountains like it wasn't even back there.
 
Appreciate the info. I’m looking at a connect & cruise from gm or maybe spear tech, same thing with the front end accessories. I’m gonna put a pencil to it today and see which one.
 
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