(Oops-double post-my bad)
Here's a couple of guys who got the carrier out without using a spreader
How to Proffesionally Remove A Dana 60 Carrier << not my spelling
http://www.youtube.com/watch?v=a2D0VpZ753Y
1994 Ford Bronco - IFS Dana 44 Carrier Removal
http://www.youtube.com/watch?v=hKPzjIz8eyk
Lucky no one got killed in that first vid. One guy's comment "Wow that cable is really tight". Priceless.
I wanna see the video when that cable snaps or the carrier cannonballs toward that dudes truck. I kinda get the feeling that those guys were gonna keep increasing the tension until SOMETHING happened. They do have a kickass garage though.
So yes you should use the spreader to reinstall the carrier. Getting the carrier out is easier than getting it back in. Think about it...
Spreading the case .010" - .015" is also how the bearing preload is set correctly and don't forget that you have to put the shims/spacers back in and that ain't gonna happen without spreading the case.
With this rear-end if the carrier can be driven in without using the spreader then the case is already effed up and will be noisy, sloppy and will end up failing prematurely.
I thinks that the rear end for your vehicle was manufactured by Dana but can't be sure without seeing it.
Dana Spicer service manual
http://www2.dana.com/pdf/AXSM-0053.pdf
Build your own spreader like this guy.
http://www.jeepforum.com/forum/f37/anyone-ever-make-case-spreader-1166623/
Good luck