SSDan highly recommends every owner getting a FSM for the year of car they're working on or have. So I know all the 76 A Body owners here should have a FSM for their car. What I'm looking for is the diameter of the front sway bar (preferably from an A Body cop car equipped with the rear sway bar). Anyone?

I have the whole 1976 smash(FSM/Electrical FSM/Parts Catalog)... That was a year they cut back on lots of things A-body... and Section 17 dealing with springs does not list the sway bar sizes...
The parts catalog has this to say....
Only the 'big' cars got rear sway bars(read: B-body).
V,L Front sway bars for the year are:
"standard" - 2948568
318/360 - 4014052

Leaf spring package shows the HD package as having 6 leafs in the rear, the 'police package' got 5 for some reason (parts section 17-11-3)

Police Torsion bars are 2948634/635 (HD/360 bars are 2535892/893)

Good luck,

-D.Idiot