Van's 2 1/4" non recording tach ??? Help needed!

[autoglide]

Has anyone used this tach on a 10...with a 540 ? Has a sending unit that screws into the mech. tach drive on back of acc case with wiring to the gauge. Van's says it will work on a 540......AC Spruce says no.
I'd appreciate all folks that can help me with answers to my question ASAP.

Thx.....Marvin

[rvbuilder2002]

The physical dimensions of the tack drive on the back of the 4 and 6 cyl engines is the same.
They both drive off of the aft end of the cam shaft.
I believe the cam shaft rotation is the same ratio for both engines.
Therefore, I think it should work for both engines (4 and 6 cyl.).