I am not disputing your information but the throw out bearing piece appears to be more suited for the 37 carbon bearing not the ball bearing on the 38. I have been wrong before and could well be this time. Tony
I see clutch pressure plate #838949 listed for 1938-41 Chevy trucks 3/4 ton and heavier. (maybe newer also, but my parts book ends at 1941)
The car and 1/2 ton pickup is completely different and I don't recognize this assembly, but maybe someone who knows big trucks can confirm the application.