[my56chevytruck]

As so many have already stated, reading that all 4 bleeders are leaking tells me something ain't right with the bleeders-threads-or seating area?? Never had to use any sealant to seat those I've worked on, but I had ONCE over tightened a bleeder and cracked the threaded area. I changed the bleeder 2 times before finding out it was cracked. As dsraven said, check (1) at a time and I would definitely buy the ones recommended for your application and replace (1) at a time. Keep us posted.