I’M CONSIDERING STARTING A NEW PROJECT AND NEED SOME INPUT PLEASE.  I HAVE AQUIRED A 1986 CJ7 THAT HAS A SHOT BODY, A FUEL INJECTED 258-ENGINE THAT I’M USING ELSEWHERE, BUT IT HAS DANA 44 AXLES WITH 3.31 GEARS AND A T5 TRANSMISSION.  MY IDEA IS TO BUILD A FUEL EFFICIENT AND LIGHT-USE OFF-ROADER, USING A NEW OUT OF THE BOX 2.5L ENGINE WITH AN ALUMINUM BODY.  THE ENGINE IS CHEAP BUT THE BODY WILL NOT BE.  I WILL HAVE TO FIND THE BRAINS FOR THE ENGINE SOMWHERE MAYBE USED MAYBE NOT DEPENDING ON THE COST.  ANY COMMENT OR IDEAS? THANKS.  

I SHOULD HAVE GIVEN MORE DETAIL ABOUT THE 2.5L ENGINE PACKAGE.  IT ICLUDES THE COMPLETE MFI SYSTEM W/THROTTLE BODY INJECTORS, FUEL RAIL AND SENSORS, EXHAUST MANIFOLD, WATER PUMP AND THERMOSTAT, TIMING COVER AND GEARS, HARMONIC BALANCER, CLUTCH AND FLYWHEEL ASSEMBLY.  

When swapping engines, you need to have the complete engine, including all accessories, engine wiring harness and computer. It is always the least expensive and least time consuming.

Several hundred dollars more, spent on a complete setup, will save many more dollars trying to make it work without a complete setup.

The 2.5L does not get better fuel economy in a Jeep than a 4.0L, and in fact sometimes gets worse fuel economy.

You can easily pickup a complete 4.0L for $1000. If you already had a complete 2.5l and were planning on offroad only with low low gears. OK. But, if your street'n and you don't have a motor yet, for the time and expense don't even think about the 2.5L.

And if you already have the 2.5L that is not complete with wiring and computer, sell it, recover your money and start off on the path that will have the highest probability of being successful.