I cannot give any hard numbers, other than my own cars that I have weighed. But in general---
74 in stock trim ~2000 - 2050 lbs
75 - 78 in stock trim - a bit heavier. Addition of heavier bumpers and smog gear - and addition of extra rear engine compartment bracing.
79 - 80 carbed - a bit heavier yet. Addition of heavier engine block, larger flywheel, 5 speed transaxle, heavier axles, heavier wheels.
81-82 FIAT fuel injection ~2160 - 2200
84 - 88 Bertone - depends. From a low of the 81-82 weights to higher with the addtion of power windows & air conditioning.
Some of the earlier models had air conditioning as well, but mostly Bertones.
Ciao,