I am having some major issues with a LTspice simulation of my EF amplifier. I am getting ringing on the lower waveform and have tried everything to stop it. The phase margin for this amp is approx 45 degrees. I am starting to think it is the spice models. Can someone please shed some light on this. Thanks.
You should take the sensible advice given by others on stopper resistors and zobel networks.
Looking at the second image there is a small notch in the wave form along with the ringing - which suggests a crossover distortion issue.
In that regard you have not cross coupled the emitters of Q29 and Q30 with a resistor (as per Self) and adopted the alternative arrangement where these are coupled by separate resistors to the load.
R35 and R36 at 200R apiece I dare say are not providing enough bias on the output devices - for the power output of your amplifier 100R would be more usual - have a look at some other designs for ideas on this point.
I think you would do better to cross couple Q29 and Q30 emitters with 100R.
The low impedance path so created allows better discharge of stored charges in the bases of the power devices. This occurs on on opposite cycle swings and speeds up the turn off process.
In the crossover region the device pairs should have similar turn on and turn of speed in order that there be no timing gap or too much overlap.