I know this is an old thread, but I wanted to follow up... for posterity. I did this at one point with 3rd gen Tacoma TRD Off Road struts. Ah, Craigslist.
The dampers are indeed near the same length. However, the Tacoma lower eyelet bushing is about 2mm narrower than the 4Runner bushing; it is the same diameter bolt hole, though. I shimmed the bushing in the control arm with a washer.
Using the Tacoma strut gave me about an inch more ride height in the front. It was also firmer. I believe the spring rate is higher on the Tacoma TRD Off Road trim strut by a fair bit.
I then put on Bilstein 5100's with stock 4runner springs, set at the third notch for 1.75" lift or so. The damping was a little better (ever so slightly more) than both stock Tacoma and 4runner dampers. I wanted the firm spring rate feel back, though, so I slapped the Taco springs on the 5100's on the second notch. This got me to more like 2" total lift with the Taco spring's / 4runner 5100's. It is a bit front-high now since I have no lift in the rear. I don't care for that so much, but easy enough to fix.
The front is still feeling underdamped to me, but I like the pitch characteristic due to front/rear spring rate now. It is closer to a dirt bike / off-road buggy / RZR feel. If I want better damping, it looks like I need spendier shocks. I am also not running a front anti-roll bar, so the firmer spring and dampers help on-road cornering feel, but only just a tiny bit... It feels great aired down off-road.
Side notes:
-Taco and 4runner spring are darn near the same free length
-4runner lower damper eyelet bushings are much more skookum than Taco, more metal, more rubber
-I'm pretty much stock everywhere else, soon to put on 285/70r17's.
