49 CFR 223.11: Requirements for locomotives built or rebuilt prior to July 1, 1980.

(a) Locomotives, other than yard locomotives, built or rebuilt prior to July 1, 1980, which are equipped in the forward and rearward end facing glazing locations of the locomotive cab windshield with a glazing material that meets the criteria for either portion of the impact testing required for a Type I test under the provisions of appendix A of this part, will not require the installation of certified glazing in the windshield location except to replace windshield glazing material that is broken or damaged.

(b) Locomotives, other than yard locomotives, built or rebuilt prior to July 1, 1980, which are equipped in all locomotive cab side facing glazing locations with a glazing material that meets the criteria for either portion of the impact testing required for a Type II test under the provisions of appendix A of this part, will not require the installation of certified glazing in the sidefacing glazing location except to replace sidefacing glazing material that is broken or damaged.

(c) Except for yard locomotives and locomotives equipped as described in paragraphs (a) and (b) of this section, locomotives built or rebuilt prior to July 1, 1980, shall be equipped with certified glazing in all locomotive cab windows.

(d) Except for yard locomotives, each locomotive that has a locomotive cab window that is broken or damaged so that the window fails to permit good visibility shall be—

(1) Placed in Designated Service within 48 hours of the time of breakage or damage; or

(2) Removed from service until the broken or damaged window is replaced with certified glazing.