I think I saw it on How Its Made, or a YouTube video, but the outer ring on the glass face is rolled and crimped to the body. There is probably a special tool to uncrimp the face dial ring.

68 Road Runner (383/4speed, post car w/decor pkg) - Major Project
69 Road Runner w/472 Hemi & 4 speed.
70 Challenger R/T SE EF8 w/ V9J, U - A32 - Major Project
2023 Ford Mach 1