Are all B body torsion bars the same for big and small blocks?
I am workind on a 66 Coronet. The bars in it have 776 BB on the end of them.

In 66 I *think* small blocks and big blocks got the same torsion bars. This was not the case later on, where big blocks got stiffer bars than small block cars. If memory serves, torsion bars are interchangeable between 1966-72 for B bodies.

Thanks for the information.

What about the K-member. Are they the same or will I need conversion mount to go from a small block to big b;ocl?

The bars are interchangeable between 1962 and 1972 B bodies; they are 41 inches long, varying diameters.

"776" bars are .88 diameter, used with small block and many 361-383 big blocks

383 HD are .90; my 64 383 4-barrel Polara was factory equipped with these; also 383 Road Runners

440s and Hemi B bodies got .92 bars

The are all the same length. The are not all the same diamter.