first, to unlock the front hubs,
jack the front end up. that will release the tension between fronts and rears, and you can unlock 'em.
then,
matchmark and unbolt the front diff input shaft from the diff, not at the xfer case. if it spins, by hand in neutral, all issues are in the front diff. if it doesn't spin you have an issue in the xfer case as well.
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would you like a "factory shop manual"? not a chilton/haynes book....
http://www.ncttora.com/fsm/87-4Runne...4runner_88.pdf
it says 4runner but covers your pu to.
rt click, save to hard drive.
cheers!
owner 93pu 4x4 3"lift