Need to Verify RPMs-Is there an OBD2 port?

[lyonboarder 4]

I have a 2007 Avalanche.  The RPMs on the dash are drastically (1,000+) different than what displays on the perfectpass.  I want to verify the correct RPMs (I think perfectpass is correct).  Is there any OBD2 port on these engines that I can read the RPMs from the computer?  Alternatively, I guess I can just use a  Laser Tachometer measured on the flywheel.

Assuming the RPM gauge is wrong, is there a way to calibrate it?

[Wylie_Tunes 146]

Technically, no. Boats do not use OBD2, but they do have on board diagnostics. An 07 could be a MEFI-5 system. You would need the setup that covers the proper gen system. 

[Troy 234]

Depending on the gauge, there is a turn dial on the back for 4, 6 or 8 cylinder .  Have you recently changed the gauge out?