727 Kick down issue.

[Sixpactogo]

I have a new development with my 65 Sport Fury. It seems to shift properly up through the gears and does not slip. Now if I am cruising at say 50 mph, and floor it to kick in the passing gear, it doesn't kick down into a lower gear. It seems to go into neutral until I let up then it goes back into 3rd gear. Anyone ever ran into that situation before? First time for me. Only thing I changed was my pan gasket was leaking and I had a new deep pan with a drain plug in it. I added the spacer and a new filter and put it back together. I can't see how that could have caused my issue. Is it an adjustment issue?

 

[66 Monaco 500 365]

To me, that sounds like your 2nd gear band is slipping, it works OK at moderate throttle, but at WOT it slips.it could be out of adjustment or your fluid level is low. make sure to check the level in neutral
My$.02