According to SHGA’s web site, their frequency is 147.580.  This does not, as far as I can tell, conform to the band plan.  We/they used to use 147.555, which also didn’t conform.  They switched when a repeater got in their way, I think.  I have been flying Marshall for a while due to covid (long story*), so I’m not sure if what their web site says is what they are actually using.

*Short(ish) version of long story:  I’m unwilling to ride up with others, or hike.  I ride my eBike up after flying.  Marshall takes much less time and effort to ride up than Kagel.  (Although, the Towers launch at Kagel might be even easier.  It does however become unsafe in my opinion if there’s any West component at all to the wind, and it was overgrown until a recent cleaning by the SHGA.  Yay!)  In any case, I’ve been flying both sites for years, so no reason not to spend more time at one than the other when needed.  :-)