With the information you've given it sounds like you've got the "remote" filter attached to the block.... plumbed with hard lines. You didn't mention the size of the lines you're using.
I have a similar modification on my 235 with the filter mounted on the firewall and plumbed to the block with 1/2" rubber lines and using AN fittings. This eliminates any possibility of engine vibrations effecting the block fittings which is what I think is happening to your setup. I was advised to use permatex thread lock (not thread sealer or RVT) on the threads in the block and haven't had any leakage issues in 8000 miles.
I really don't have a simple solution for your dilemma other than to bite-the-bullet and eliminate the potential for future leaks by using the soft lines. Mounting your filter remotely where your block fittings get no stress, will cure your leakage issues. I have pictures of my install in my Webshots "Tips and Tricks" album on pages 6 and 7. Hope this helps.
Dave
Last edited by Fla54Chevy3100; 06/14/09 02:29 PM.