GTX 23 ES & G3X Manual Error?

Trying to determine if there is an error in my thinking or an error in the manuals.

GTX 23 ES transponder manual shows P2301 pin 43 as RS-232 Ground (connecting to G3X GSU 73 signal ground pin 40).

However, G3X Install manual revG shows GSU73 pin 40 should connect to GTX 23ES connector pin 51 (signal ground).

According to the GTX 23 manual, pin 51 (signal ground) is associated with the ARINC group (not the RS-232 group).

Thus I suspect the G3X manual is wrong about using pin 51 on the GTX and I should instead use pin 43 (RS-232 ground 1) on the GTX (to connect to gsu73 pin 40)?

Which is correct...anyone else confused by this?

Very respectfully,
Jim Clark

Another descrepancy?

GTX 23 ES manual shows to use GTN650 p1001 pin 40 as the signal ground paired with p1001 pin 8 (TSOA ADS-B GPS rs232 1 out). However, gtn650 manual (web download random link) shows gtn650 p1001 pin 46 as rs232 gnd 1. Which pin on the gtn650 should be used to supply the ground for rs232 1 ads-b gps serial data?

Very respectfully,
Jim Clark