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

Is this correct? I've never had one of these apart, nor has my friend that I'll be helping do the swap.. HELP!