You might try www.fordracingparts.com. I know they always tell the weight of each product on there and they've got quite a few complete engines, including the GT500 and Ford GT motors
For the 98 cars, heres a few numbers:
Cast Iron Block: 154 lbs
Alum Alloy: 85 lbs
Alum cyl head: 33 lbs
Alum Alloy: 38.5
composite Intake Manifold: 4.5 lbs
alum alloy: 20.5
Exhaust Manifolds: Cast Iron Nodular 20.9 lbs (15 for cali)
Nodular Iron/Silmoly: 7.5 for left side, 7.1 for right
now to skip all that bs check this out
Dry Weight for 4.6 sohc : 529 with man/492 auto
Dry Weight for 4.6 DOHC: 535
Cast Iron Block: 154 lbs
Alum Alloy: 85 lbs
Alum cyl head: 33 lbs
Alum Alloy: 38.5
composite Intake Manifold: 4.5 lbs
alum alloy: 20.5
Exhaust Manifolds: Cast Iron Nodular 20.9 lbs (15 for cali)
Nodular Iron/Silmoly: 7.5 for left side, 7.1 for right
now to skip all that bs check this out
Dry Weight for 4.6 sohc : 529 with man/492 auto
Dry Weight for 4.6 DOHC: 535
yea why would an auto tranny be lighter. the manual trans are so much smaller than an auto.