I don't know how to append my message to the original discussion...

Anyway, thanks for the suggestions as to how to seal the flange joint where the collector pipe attaches to the front and rear exhaust pipes.  I tried the "exhaust patch goop" as suggested by Gene P.   I had to buy a big tube of it (lifetime supply I hope.  $30.00) from NAPA, but it seems to have worked! I had to smile when I read the directions on the tube that said "apply a � inch thick bead"!  The stuff dried hard and if it hangs in there I will be quite pleased and it will save a lot of frustration in future Vanagon exhaust pipe replacements.

Thanks again!

Mike V.