20 CFR § 220.127 - When the only work experience is arduous unskilled physical labor.
(a)Arduous work. Arduous work is primarily physical work requiring a high level of strength or endurance. The Board will consider the claimant unable to do lighter work and therefore, disabled if he or she has -
(1) A marginal education (see § 220.129);
(2) Work experience of 35 years or more during which he or she did arduous unskilled physical labor; and
(3) A severe impairment which no longer allows him or her to do arduous unskilled physical labor.
(1) The claimant is working or has worked despite his or her impairment(s) (except where work is sporadic or not medically advisable); or
(2) Evidence shows that the claimant has training or past work experience which enables him or her to do substantial gainful activity in another occupation with his or her impairment, either full-time or on reasonably regular part-time basis.