Non Lockup To Lockup

The lockup has a like 5/8" smooth button on the end of the input shaft, whereas the non lockup is splined all the way to the end.

I don't know WTF I'm thinkin. A lockup transmission ain't gonna get me anymore than 1:1 and I have that RIGHT NOW with a three speed. lol

42RH? Isn’t that the non electric over drive 904?