4 Wheel Drive/SUVs: 2wd to 4wd conversion, toyota 4 runner, drive train

Question
I have a 1998 Toyota 4 runner 2wd and want to convert it to a 4wd is this possible.

Answer
I am sure it could be done, but the cost would be prohibitive.  The only economically feasible conversion would be to find a compatible 4runner with four wheel drive and switch the entire drive train.  I am not sure if the chassis is the same for 4wd as it is for 2wd.  In any case I wish you the best of luck.  Bud