Hemi Conversion: Does it matter if donor truck is a 3/4 ton vs a 1/2 ton?

hardtailpan

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So, I found another possible hemi donor truck. This motor runs, but its in a 3/4 ton. I don't *think* there is any difference in the motors between 1/2 ton and 3/4 ton, but if someone knows better, please let me know. Also, from a motor swap legality standpoint, is it legal to swap a motor from a 3/4 ton truck into a jeep TJ? The year of jeep and truck are both the same, so that is not an issue.
 
Likely not at all...it's going to be a maze to marry 2 dissimilar vehicles any way you go. Years back the the 3/4 ton might have a 4 bolt main or something, but likely not real issue in chassis size...the challenge is mostly electrical.
 
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Likely not at all...it's going to be a maze to marry 2 dissimilar vehicles any way you go. Years back the the 3/4 ton might have a 4 bolt main or something, but likely not real issue in chassis size...the challenge is mostly electrical.
Thanks Andy. The reading I've been doing recommends the Ram Hemis. I agree with you that there is likely no difference, tho there appears to be differences among others, say Jeep hemis. I haven't googled what or why as I always planned on using a Ram motor. I do wonder if using the 3/4 ton motor would be legal for say, a California smog inspection. I don't know if there are limits on that and i'd like to keep it legal. I believe over 10,000 GVW the emission laws are completely different, so it's more likely that some of the 1 tons might not be legal.

I completely agree with you that the challenge is mostly electrical. I think hotwire auto will help with a lot of that, unless I decide to piece together my own harness. The Ram and the Jeep I am considering are the same year, and the computer bus architecture is the same which solves some of the problems.
 
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IIRC, for the Gen3 5.7 Hemi‘s in the Ram there is no difference in the engine between the 1/2 and 3/4 ton, although I believe it is easier to find a mill without the MDS in the 3/4. My engine started as a 5.7 from a 2006 3500 ram, without MDS. Not a big deal either way, as it is easily deleted. As long as you are equal to or newer than the year of your Jeep, you will be fine with emissions. If you go with an ‘06 or newer Gen3, to play nicely with your electronics, you will need an ECU from an ‘05 or prior.

Here is mine after stroking to 392...

165E1987-190A-4F6F-BE0D-65182D8DD154.jpeg


The best advice I can give on the 5.7 swap is to pick up Jim Beebe’s Hemi swap guide from Red Rock Off-road / Red Rock Wiring in Michigan.
 
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