Front Bearing retainer for 1963 T-10D-1 cases, and 1963 only Muncie cases ending in "704" using a threaded input [similar to a later  Muncie] and a 6207 front bearing .this retainer is designed for the normal GM bell Housing Castings ending in 403, 383, and other cast iron bells [ not the 1963 bell housing with the smaller opening for retainer]