ok, well I found a 91 explorer for my father for 500 bucks.

it's a 4X4 4.0 ohv eddie bauer.

he had my aunt pick it up before he could see it (stupid)

the guy claimed it only had a bad radiator, and that he had replaced all the hoses and accessories on the front of the engine. well....

he did do those things, but he left out that he appearently got it hot enough to either blow a head gasket or crack a head. I know it's the revised 4.0, but the cologn is still suceptible to cracked heads at high opperating temps (like a dumb arse kid overheating it constantly)

my father checked the ATF since he knew it had been gotten really hot, and found some mystery silver fluid. I've never heard of silver/grey atf before, any ideas there? my father also says it looks like a replacement trans. the jack shaft from the tranfer case to the front diff is also missing (scary)

as far as the engine, how plug&play is it to just drop a SOHC cologne 4.0 in the ohv's place? do they both use eec-IV? or is the sohc engine a later EEC system like the contour? are the sensors compatible?

if it's simple enough for my old small block mechanic father, I would think it's well worth it for the extra 55HP and extended EPA ratings.

on the other hand, if the heads are good, gasket sets for the old engine are very cheap and simple to install.

IDK, just looking for some opinions for my pops.

let me know what you think

PS: Ironic me AND my father are now both the proud owners of fords with blown engines, WTF

Extended EPA ratings? The EPA will technically only allow a vehicle to posess an engine with better emissions than those tested for highway use in the stock automobile. There's a tag in the center of your hood that says the vehicle passed all emissions requirements for year 199X. Technically, you'd have to have your new vehicle+engine combination retested at an EPA certified laboratory, and pass those test requirements of the model year of the base vehicle (not the engine). The penalty for non-compliance is the destruction of your vehicle or removal of the non-compliant motor. Vehicles over twenty-one years old are exempt, so in a couple of years you could put your repaired 2.5l Duratec (and all of its emissions parts) into the '91 Explorer, legally. You could have the greenest Explorer on the planet, since "light truck" emissions standards were looser than for automobiles.

a sohc engine is 97+, the ohv is in a 91. rule with emmisions in engine swaps is you can only swap in later model engines.

that wasn't what I meant though, I meant the sohc would get better MPG ratings. they refere to fuel economy as "epa rating" on some consumer reporting sites.

any body know if it would work?

also really need to know about the silver mystery fluid.