The AFV NEWS web site lists over 600 plan 4-view drawings of various AFVs, from WWI, WW2 and through to the Modern era. They sell for $2.00 each as letter size laser printouts.
They are available in 1/35, 1/48, 1/72 or 1/76 scale. (or any other scale under 1:35)
for the complete listing.