yes all same door shells '77-87
very easy conversion
all you have to do is bolt in the manual regulators
nothing else differs
have to use '77-up regulators because the crank shafts are longer after '76 because door panels were made bigger and thicker starting this year.
and new door shell design to allow power door option in which was not available until this year in the trucks
even though to the average person who doesnt know gm trucks they look the exact same '73-87(91)
even 77-80 was a different year group in itself as well, because they used a short 4 year style of interior door handle and other things. and technically the '77-80 door panels are different from '81-up but internal parts are all the same through 87(91)