Just bought everything for 3.73 gears

So getting ready to swap the gears, I have4 a really great shape 741 case, bearings, and seals frankly..

My install kit didn't come with a crush sleeve, my 68 service manual says "spacer" with shims on either side

Only the 489 uses a crush sleeve. Your 741 has a sleeve and uses thin shims. When you take it apart you can see that easily