The Clearfield Progress is available online via Ancesty.com up through 1975, so For Kenneth's obit from 1983, I would write to the Clearfield Historical Society and/or the Clearfield Library.
Kenneth and Donald were both on the Social Security Death Index.
I did find Donald's obit:
Clearfield Progress 30 Oct 1967, pg 2
NORTH TONAWANDA, NY – Donald Walker of North Tonawanda, brother of Kenneth Walker of Clearfield, Pa., died yesterday, October 29. Funeral Services and interment will be Wednesday at North Tonawanda. Born in Bennetts Valley, Pa., he was a son of the late John and Lilly (Wheeler) Walker. A sister, Mrs. Kyle (Margaret) Graham and a brother James Walker also preceded him in death. In addition to his brother at Clearfield he is survived by two sisters: Mrs. Sarah Lazorchak, St. Petersburg, Fla.; and Mrs. Eliza Strittmatter, Patton, Pa.
Could not find family at all on the 1910 or 1920 census, but on the 1930 census:
1930 Census Altoona, Blair Co., PA, Enumeration District #29, Dated: 14-15 Apr 1930, Sheet #8-A at 2000 Union Avenue, Dwelling #148, Family #206 (must be apartment):
1) Walker, Anna L., head, renting for $35, age 43, widow, mrd at age 21, born PA, Parents born PA, Occp: Clerk NOTE: Middle initial might be an “S”
2) Walker, William R., son, age 21, single, born PA, Parents born PA
3) Walker, Donald F., son, age 16, single, born PA, Parents born PA (right age to be your Donald)
Found a few more details of the sisters mentioned in obit which I will email you directly and based on those details it looks like John Walker may have been married once before or Anna Walker's age and her age at first marriage is incorrect on the 1930 census.