What about this steering arm from CPP. it bolts to the top two brake backplate boltholes in the spindle using 7/16" bolts. The steering arm is made to work with the Saginaw power steering conversion, so should work for you if the '38 spindles have the same bolt pitch as the later ones.

Stuart.

1950 Chevrolet 3100 (occasionally working) truck:https://c2.staticflickr.com/6/5490/30684982201_6dc479d18d_c.jpg
1928 Chevrolet AB National Phaeton: https://c4.staticflickr.com/6/5573/30137792083_42886d30a4_c.jpg
1932 Austin Special Sports: https://c8.staticflickr.com/6/5793/30116567183_1520e67c4d_z.jpg