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Thoughts on 5.3 swap - Auto or Manual in an MJ?

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I’ve got a LM7, auto and TC from a 03’ Chevy truck, With the harness and computer.  I really don’t want an auto or the electric shifted transfer case.  Id prefer to keep the Jeep transmission, I have a 4:1 241J and spare AX15s.  An NV4500 and 241J would be better though.  


Anyway, behind a 5.3 in an MJ what transmission would you prefer?  Who else has done this swap?


The MJ has full width 44/60 axles and 4.10 gears, will run on 35” or 37” Maxxis bias ply tires.  


Old pic. :)




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We did a 5.3/4500 swap in a Scout at the shop I was at. Had plenty of power and it was fun to drive!  I seem to remember the only way to put the 4500 behind the 5.3 was with a pricey bell housing from Advance Adapters. Others have done 4.8/5.3 swaps with AX15s as well though I haven’t personally seen one. 


Good to to see you again! :beerchug:

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I’ve been too busy to do much Jeep work lately,  I’ve been farming out most all of the  maintenance on the family Jeep fleet lately.   I’m probably gonna have a shop prep the accessories for this engine and source a lower intake so I can fit it under the stock hood.  


Looking at kiwk performance for a accessory package and I’m really close to getting that Holley intake system for it.  Might have a guy on FB do the harness... the Harness swap shop, Novak mounts, headers and Radiator.  


LSs are new to me :) so I’m trying to figure it all out.  Been driving nothing but Jeeps for the last 20 some years.  






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I see this question a lot on FB swap forums, many will say use the 4L60e for simplicity.  I think it really boils down to which you prefer.


Not an MJ, but here are the quick specs on my CJ7:



Dana 300 4:1

Dana 44 front and rear, 4.56



The NV3550 has held up after two years and multiple wheeling trips.  I've never owned an AX15, and I've heard different things.  Some say they are comparable to the 3550, others say it's not as strong.


I've got a NV4500 and thought about running it.  But the extra length, weight, and probable mods to the floor board, plus no problems with the 3550, keep me with the 3550.


I think 4.10 gears will be a little high for 35s and 37s.  4.56 for 35s or 4.88s for 37s will give better performance off the line and make the overdrive more usable.  

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