Done a couple dozen gear swaps over the years and never used a spreader and never had an issue. A spreader would make life easier for sure in place of pry bars and a deadblow hammer. I made some set-up bearings years ago and it makes the job much easier. Spreaders are pretty cheap now on Ebay and Amazon
Gus
I don't use a case spreader, never have, never will
I remove the center section by using a pry bar gently to work it out a little at a time and then remove the bearing and shims with a bearing puller
, I made some set up bearing like Gus uses and use them to set up the new gears and get the preload and back lash correct and then either press on the old bearing with the new shim stack or with the new bearings and races if their getting changed out with the new shims
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I'll use enough shims to get zero preload with no ring gear on the center section and then add another .012 to .015 additional shims for preload depending on which works the best
i use a plastic or leather mallet to tap in the center section, very carefully
