I don't know the 23B coupler height, but as a last resort a call to Jayco should get the info you need.
Just a heads-up on the Reese HP Dual Cam ...........;
When you go to mount the Reese HP 'frame plate' to the HTT's A-frame, check your location dimensions at least twice and insure that there aren't any gaps between the frame plate surfaces and the A-frame surfaces before drilling (large C-clamp works great). Maintaining the specified torque specs for the thread-forming screws @ the frame plate is important (don't guess).
One thing that many folks overlook is the proper chain assembly/mounting of the hanger bracket to the cam arm, please note:
New HP Version:
Older HP Version:
Enjoy the new HTT
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)