with help from the '70 Parts Catalog

manual steering box housing
part # 2537 347 6-cyl A-bodies (#2537 3?? casting) bushing
part # 2537 346 B & E-bodies and 8-cyl A-bodies (#2537 349 casting) bearing

first digit E, F, G = model year '69, '70, '71 & the G, H, J = revision numbers?

here are a couple more unknown origins