If you look in a GM "Parts history book" , your 3901698 is superceded or changed to 3968773 . I think a good explanation for this might be DC Versus YS . Then to really confuse you , 1981 Chevy Corvette only parts book lists 3968773 for ONLY 1967 Corvette. What this means in this particular book , since only 67 Corvettes used the 15x6 rally,, the REPLACEMENT part is, or only thing Chevy had available to fix your 67 vette in 1981 was the 1970 15x6 3968773 part numbered wheel. Same wheel in offset size and shape as all 1967-1970 15x6 DC YS wheels , CAR and WAGON.
The absolute BEST wheel book is Chevrolet by the Numbers . It lists everything by Code. All of the authors code information came directly from the GM Archives