This is the wheel style discussed in this (http://www.pirate4x4.com/forum/showthread.php?t=231554&highlight=wheels+Chevy) thread.

They're chevy, from 88-97? off of half ton 4x4s and vans. The other style of wheel is slotted around the outside (like the old Rally style), and has to have the welds cut to make work.

These on the other hand, only need to have the 12 rivets drilled, filled, and press the center in backwards (after you've opened up the center hole.)

They were made in 15 and 16" as far as I know, and came in a five, six, and eight lug.

Brian, thanks for coming through with the pics...I've been wondering what the riveted wheels looked like, and didn't realize they were of such recent vintage. Thanks!!
Hope the 6AT tweaking is productive...

Steve