I considered a JDM for my 4x4 tacoma project i did 2 years ago but after looking at pics of them i saw that the oil cooler and oil filter were in reversed locations, alternator looked different and i read that the emissions equipment wasn't the same. I read it's no big deal to change out the parts but then i found a 69k mile 3.4 out of a wrecked 03 tacoma so i went that route.
My JDM engine came out of a Hiace--- which is a large van. It came on a pallet, strapped all complete from fan attached, cut rad hoses and wiring harness back to the rear of the engine block. As T4R2014 says... and as I mentioned, everything was different. I basically, put both engines on stands side by side, and swapped the bolt-on components--- fuel system/intake, exhaust manifolds, crossover, oil cooler (cleaned it out well and ordered new o-rings from Camelback or Toyota of Dallas, can't remember which!), oil pump pickup and pan, fan bracket (the JDM was 3/4" taller), and I replaced the TB/WP and all gaskets and seals, as I stated before. None of it was hard---- just followed the torque specs in the service manual. This may seem obvious, but I'll mention it, I swapped the PS bracket but I didn't mention it above because when I prepared to pull the old engine, (as well as disconnecting the wiring harness and folding it back under the wipers) I unbolted the PS bracket as well as the AC compressor, and strapped them to the side of the engine bay. No need to disturb those pressure lines!
JDM is by no means the cheapest alternative---I paid a fair bit, hoping I was getting an engine as advertised (this may have been naive!) I was lucky however, and everything has worked out so far. I've seen threads since, of guys that weren't so lucky--- bottom line is its a used engine--- there are no guarantees-- it just depends more on who you deal with.
Sounds like you found an engine locally so you probably paid less for it, than I. As I hadn't performed an engine replacement, for sometime, and never on a Toyota, I did a fair bit of research, took my time, and cross-referenced OE part numbers to check compatibility--- thats how I discovered my JDM came from a Hiace! So I had a ton of info even before I had the engines sitting beside each other--- then most of the differences were clearly visual. If I was to do this job again, I'd be able to do it in a fraction of the time. Since you've said you did this job on a Tacoma a couple of years ago, I imagine your only concerns were compatibility. I hope I've been able to offer some helpful and useful info, for you and the next guy who takes this project on! Again, good luck!
PS: this afternoon I'm dropping the rear suspension with drum brakes, on my sons' Mitsubishi Eclipse and swapping it out with a totally re-built assembly with disc brakes... hopefully, he'll learn some more skills an we'll have some fun!
