Display screen size issue with Centos 6.3

[Tigger_the_cat]

Hi, This may be the same as issue "Display Resolution problem on Centos 6.2 Guest (#17729) raised in 2018. If so - please let me know.

I am unable to get the screen output to fill the screen. In Centos: System->Preferences->Display gives the best resolution as 1024 x 768 and the screen is shown as "Unknown". In the in Guest Centos VB -> View-tab - the "Auto-resize Guest Display" option is greyed out.

I have the following system:
Dell Optiplex 7010 running Linux Mint (LM) 19.2 as host OS
VirtualBox (included for this distro) v5.2.34_Ubuntu r133883
All LM 19.2 updates applied
MSI graphics card Geforce GT 710
HP Elite Display E231 23" wide screen monitor
Guest Centos 6.3 has been installed as a full development workstation - so all packages possible installed.

The Guest Additions have been applied (5.2.34) - see attachment for output. there are no obvious errors, but shouldn't there be more lines (with green OKs)? Can anyone help?