Series or Defender? On a Series, sure, you have to move the front cross member forward. On a Defender it's not an issue. Anyways, I don't want to derail the thread, I just wanted to show that a 6 cyl is very possible if you don't mind doing some minor modifications. Mine had a 4 cyl bulkhead, a massive Banks intercooler, a 3 core rad, a 200 amp alt, power steering and hydroboost, and everything fit quite well, but it was tight and it took a long time to package everything. The new truck is quite a bit better laid out, the 5 speed cuts down on the plumbing (no cooler, kickdown etc).
Here's a video of it on the trail shot by LShobie in Weir Qc... It's been posted here before and the Land-Cruiser guys love to make fun of the broken Land-Rovers!!!
In My case, a Toyota part failed, the FZJ80 rear e-locker motor fried and would not lock the rear end...
LandRovers vs Land Cruiser - YouTube