Here is the in-depth write-up that I hope can serve as a how-to for OM617-swapping 96-04 Tacomas/4Runners (and T100's).
I picked up this $600 1997 4Runner 5VZ/A340 4x4 (rear e-locker) with roughly 250k miles and it was SHOT! Completely rusted out even though the body doesn't show it. Destroyed interior. Radiator blew up and mixed trans fluid with coolant to make a milkshake in the trans. Now I haven't read a single report of anyone flushing their trans and successfully driving it after that. Even the ones done under warranty at the dealership with the power flush had trans failure shortly after. Keep an eye on your radiator if you've got an automatic! The PO claims he noticed it right away and had it towed home where I picked it up. I flush the trans, added a new radiator, and put another 30k on the 5VZ! I daily drove it to work, used it to tow the mower trailer around, and even drove it 3 hours into Iowa with the trailer to get a band saw. Did a fair amount of wheeling with it, too, enjoying the rear locker. Eventually, it started losing coolant, so the 5VZ got yanked and sold.
The plan for this has always been for R&D. The only money I have into this rig is the new radiator and mounting the free tires someone was throwing away. Sold the 5VZ to cover the purchase. Can't beat that! I'm currently swapping in an OM617. I'll be using the 4Reigner to test trails I'm cutting in our pasture, as well as haul the tree cutting equipment around. Since the frame is already falling apart, I don't expect to keep this around much longer. I had originally planned to do a TDI swap after the 617, but have since decided not to worry about making TDI adapters for the Toyota Automatics, as the torque converter pilot stub would require turning down, and that is probably too much effort for most people. Once the frame folds in half, I'll pull the 617 back out to go into something long-term, and I'll save the rear axle and trans.
Here begins the massive photo dump... If you've never cleaned your AC evaporator or heater core before, you need to try this stuff!! https://amzn.to/3UpNSZ0
It goes in thru your evaporator drain, foams up, then drips out. I highly doubt mine was ever cleaned. It leaves a minty-fresh scent in the air ducts. My AC works fantastically.
Speaking of creature comforts, I find myself adding more and more. The 3rd Gen 4Runner vents are available new, here: https://amzn.to/3EkQD8k
Mine was broken and nasty. This one is a perfect match.
I also successfully got a fob for the 97 (here: https://amzn.to/3WMgjlD) and the 2001 (here: https://amzn.to/3UqoVwD)
The programming for the 97 was stupid-simple. The 01 sucked! Here's the manual for the RS3000
Now, you see, my 4Runner didn't come with a key for the doors - just the ignition. And of course, no fob, either. So now, for the first time ever, I can lock my doors! Apparently the PO had replaced the ignition cylinder but wasn't smart enough to have things re-keyed. I'll be doing this in a couple of days.
I also wanted a cup holder. So I ordered this factory replacement, which to my surprise for amazon stuff, is another perfect fit. https://amzn.to/3A16tCC
I think I'll be making a cup holder out of the old t-case shifter hole, eventually, as this terribly placed holder blocks the HVAC controls and barely holds anything larger than a can.
Also found a replacement center console lid for $42. The latch doesn't work, but at least my elbow no longer gets pinched. Really wish these seats had arm rests.
Added a lace-on steering wheel cover, and these are my favorite. My original Toyota came with one, and I've never found anything else I've liked more. All the grip you could ever want.
Lastly, I went to work on the rear wiper. First, I removed the entire arm and cleaned, then soaked in oil to get it to move again. Now it moves like it's new. Then, I put these adapters on so I can run a cheap/normal 13" blade. https://amzn.to/3X1uGmr
https://amzn.to/3G86oBb I happened to go by a free CO-OP scale, so I weighed 4Reigner with me an Dolly Parton in it. We weigh a combined 250 lbs, so 4Reigner weighs about 4170. This is with the Tundra brakes and rock sliders, without a spare tire.