swapping 14L for 12.7 ddec V

I am too the point I am going to have to inframe my 14L or replace it. I only tow my 22k fifth wheel and carry smartcar behind cab. 12.7 plenty of motor. I should get better mpg with the smaller detroit. It is know for better. My thinking if both are ddec V motors it should be direct swap. Price I got for inframe on mine is 12-14k. I also understand the later 12.7 had the smaller bull gear and more reliable. Do you see any problem with this idea. I do have an ultrashift. But my computer should work with another ddec motor, right?

 

also if I do an inframe it would take me years just to brake it in. Would an 500k mileage used motor be a better deal?

 

It is pucking oil out downdraft tube. Gets on my 5th wheel. It has since I got it had a mist like but didn't do anything but leave a dark spot on ground. It now leaves a wet spot on ground. My truck is singled. My ramps to load my Smartcar are at back under flatbed. it gets coated in oil also. Yes. an inframe is head, liners, pistons, bearings, gaskets and deck milled if needed. quoted me 14k if need milling. My truck cranks good, has good power but I haul light. I really think I would just get cylinder kit, bearings and reuse the head. I might put 100k miles in 10 years. 780k miles

 

no, i have egr.