It does load the nvidia-driver, an old one but if it worked before it should still be ok.
Just before it fails to load GLX:
(WW) NVIDIA(0): Failed to verify AGP usage
This makes me think it might be AGP related. Did you compile the nvidia-driver with or without freebsd_agp? Is AGP in your kernel? Is it loaded as a module? On 5.x and higher this is done in /boot/loader.conf. A line agp_load="YES" will load the freebsd AGP module. IIRC 4.x should work the same but I'm not sure if agp is build into the generic kernel of 4.x though.
Hmmm.... interesting thought. I checked the current kernel and the line
is in it and not commented out. No other reference to agp though. I added the line agp_load="YES" to my /boot/loader.conf file and rebooted to see what would happen. Unfortunately, this did not change the problem or the XFree86.0.log file errors. I have extensive notes from when I installed the NVIDIA driver originally and there is no mention there of having to do anything about AGP. My video card is not an AGP card.
So, I remain stumped. My gut is telling me that the problem must be related to something that did not copy to the backup hard drive such as a file or directory. I have done this kind of hard drive switch in the past without this kind of problem, although I can't remember if I have done it since I installed this video card and driver.
I really appreciate your time and effort on my behalf. If anything else occurs to you, please let me know.