Here's what changed though...when I had the gamma arm at 90' with the 14 gauge gamma wire 24" away from the tower I was able to insert my Johnson 60-160pf variable cap in series with the gamma wire to get approx 58-60 ohms at X=20. The cap was 2/3 meshed at this point. >>>

That's the right way. You have to cancel the reatcance of the drop arm to get a good reading. Maybe you need a larger capacitor to hit the bottom of the band? Resistance normally goes up in a case like yours as frequency is drecreased.

<<<NOW that I've lowered the gamma arm to the 67' level...I insert my variable cap and the antenna resonates at 1.970 MHz with R=36 ohms and X=0. For some odd reason the MFJ SWR reading shows 1.0:1 with this 36 ohm reading and, inside the shack, the Ft1000D shows 1.0:1 swr from 1.988 to 1.950 and a 1.5:1 range of 2.007 to 1.930>>>

What does more capacitance do?

<<<<It now appears that the antenna is a bit short but why am I seeing these crazy high resistance readings with no variable cap in line?>>>

You should see them. The MFJ detector is a 50 ohm bridge. It will overflow and give all kinds of goofy readings when impedance is far away from 50 ohms.

<<How can I lower the resonant freq without moving the gamma arm up? Increase the spacing of the gamma wire from the tower? Add more radials?>>>

I would have left it at the top and shorted the wire to the tower at different places until I found the sweet spot. But you have to dip the reactance out to really know what you have.

<<<
I was going to build a three conductor wire cage with the wires spaced 10" apart or so once I had an idea where the antenna resonates. Would a fatter gamma trio drop the resonant freq or just change the capacitance value of the antenna?>>>

A fatter shunt wire will lower reactance and resistance. You will need more C, and the tuned resistance will be a bit lower.
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