I have a '96 Ranger with a 2.3 that's got close to 190,000 miles on it, engine still runs great, uses no oil but the bottom end rattles for a couple a seconds on cold start up. I found a '99 2.5 CHEAP with low miles. Looks the same.... will the 2.5 just drop in??

 

The 2.5 should be pretty much a drop-in swap. You may need to swap out a couple sensors from the 2.3L, as there could be some difference between 96 and 99. At least both are OBD-II and use the same ECU controlled ignition system. The harder swap would be a 2.5L into a pre-95, but even that is doable.
Externally, these 2 engines are the same. The difference is crank, rods, and pistons.

 

Rogue Wulff, thank you Sir, that's the answer I was hoping to here!

 

just did that swap 3 weeks ago.no problems i even used the 2.5 pan and the injectors from the 2.5.you just have to use the fuel rail from you 2.3 and valve cover.i think the header on the 96 is better than the manifold so i used it to.i rebuilt mine before i installed it and love it.just hauled around a ton in it over the weekend and never had to shift out of 5th all the way home around 50 miles up and down hills.good luck

 

Quesey, thanks for the reply. The engine I'm going to use is a '99 with less than a 100,000 miles, I'll check compression, pull the pan and check the bottom end, if everything looks good I'll take a weekend and swap them out.