Working with 3D printing replacement early A-body parts

Again.... Print em up, leave em in the sun, expose them to 140 degree and -20 degree interior temps and subject em to countless vibratory cycles of various amplitude and frequency for 1500 hours, and we'll talk about it in twenty or thirty years.
It won't take20 years.

ABS filament isn't uv safe. ASA is a little better but the overall problem with ABS is it's designed for molds, not FDM printing. When ABS cools it shrinks away from the mold aiding in it's release.

If anyone is going to use ABS, that shrink needs to be taken into account. In fact all FDM filaments shrink to some extent, but the ones that shink the least, PLA etc, are also the ones that melt/deform at the lowest temps.

Dash vents are not going to survive the heat for very long.

I printed my badge holder work out of PETG and left it on the passenger seat once, it warped pretty bad, lol.