Red part------
you should learn to search for wiki first before making comments here....
http://en.wikipedia.org/wiki/M47_Patton
http://en.wikipedia.org/wiki/M48_Patton
where it is said that it was produced in late 40s??????
for blue part-----
learn the difference between a light tank and a MBT before coming to a defence forum..you're saying that someone bought a bicycle over an aircraft..
for green------
I don't even want to reply as your post is as dumb as it ever could be..a tank doesn't become light by doing yoga..it has to sacrifice almost everything to reduce 20 ton.armor,guns,equipment,powerful engine--everything.but then again,it doesn't matter to you as for you,PT-76 and T-72 are same...
and for black part.....
I did the same.I compared it with tanks during 1965 and not today.today,a capable ATGM carrier can destroy a MBT with being 1/3 of its weight.but not back then.weight was the key factor as people wanted heavier(more armor,more punch) tanks to counter light tanks.you should read about difference between light british tanks and heavy panzers of Germany and their fate during various battles..German tanks blew them up without even breaking sweat.and now,you're comparing a tank with armor 120 mm against a tank having armor 10-40 mm..
and I didn't expect a rational reply from you,as I know,you're uncapable to gobble up so many information.go home and get a good sleep.and start reading about tanks from tomorrow.else,don't bother to reply.
leave him..he is seriously a ret@rd..he is comparing an MBT(armor-120mm,gun 90 mm) with a light tank (rmor 10-40 mm,gun 75 mm)..