I can't comment in respect to the Equali-z-er WDH, but I went through the same process with my Reese WDH back in 2016.
I went with a Curt 2 1/2" receiver shank with my 2" Reese Ball Mount. Compatibility was good, but I did have to use a couple 'shims' between the shank and ball mount in order to insure proper fit-up before meeting the bolt(s) torque requirements.
I went with the Curt 2 1/2" shank because at the time Reese's version wasn't available. Curt Shank item #17128......., $99 back in 2016.
JOF thread on using Shank/Ball Mount 'shims':
https://www.jaycoowners.com/forums/f...bly-38323.html
Set-up has worked great to-date.
Bob
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2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)