On my 87 I was able to get it out the top, but there was only one way it would work. Read here for details:
Alternator Removal


'87 Xtra Cab, 4wd, 22r, 5spd
'92 Xtra Cab, 4wd, 2L-TE diesel swap, 5spd
http://toyotadiesel.com/forums/showthread.php?t=2502