auto gearbox upgrade

I have a mk1 1982 1.5 gl auto. can anyone tellme if a 18oo cc aut box will fit my car, and the advantages and dissadvantages of this, as i believeif the car is driven carefully,it may be ok

many thanks

hi i have a 1600 auto g/box if ur intrested it only done 45000 miles genuine

SFA difference in these 2 boxes.