Are you getting the Speed Bleeders (from the company by the same name) or the Russell versions?? I have heard a lot of stories about the Russell versions havng leakage problems.
I have a set of Speed Bleeders on my 87 and so far, I have had no problems at all. Speed Bleeder sells a small bottle of sealer that you can use to replace the original sealant. After a dozen or so cycles of loosening and re-tightening, the sealer will begin to come off and it needs to be re-applied to insure an effective seal.
Just make sure the the threads in the calipers are in good shape. Follow the instruction carefully for the initial installation and you will be OK.
When I bought my Speed Bleeders, I got the bleeding kit (a 3' length of tubing and a plastic bag to hold the old fluid) and it was well worth the 6 or so dollars. The sealant was about $10 so I got it at the same time. I do a lot of autocross and some track days so I frequently bleed the brakes. The Speed Bleeders make it easy to do by myself.
