the 47 no, the 45 however was brought over and its parts are the same other then the diesel motor. and all the axles of the same era/spline are the same. yes, birf is bigger on an 80, again though, thats still a matter of metallurgy. steel has changed over the last 100 years. notice how a 60 year old car in a field beat by the elements day in day out for 50 years wont have any rot, just surface rust? thats cause the metal wasnt cut like cheap coke. as far as ive been told.
I can buy a TG HD birf for my 40 that is undeniably stronger then an oem 80 birf, and is still undeniably smaller as well, jus sayin. so accounting for diminishing steel quality i personally would design my parts larger to account for it. and I imagine thats what toyota did. so not necessarily making them stronger. not fighting to win

just trying to consider all the variables on top of the more obvious ones. if anyones done considerable wheeling on both and broken more of one then the other id be more convinced.