[is there anything different than the manual info to disassemble a pre-safety gun or is it the same?] -
Samo-samo.
[Is replacing the extractor a DIY(drop-in) fit or is it a gunsmith job?] -
It's not a hard job, but it's also not one for an inexperienced amateur (aka:drop-in).
[I usually use weaver style bases and rings on my rifles and notice that weaver,leupold etc sell bases...which one should i get] -
YMMV. I use receiver peep sights on my leverguns, but for other scoped rifles, I like the light weight of Weaver rings/bases (I use the Weaver base with the sighting trench for iron sight use) - but have Leupold/etc on some of my other rifles.
Other folks often use the Weaver base with some other Weaver-type attaching bases, like Warne, etc.
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