rearend issues

I have a 1986 chevy k10. putting 91 rearend into it. Was wondering 3:42 in new rearend and 3:08 in old one have to change front diff gears and modify spring pads along with cutting bump blocks out. Do I have to change anything else? tranny or transfer case?

Salvage yard interchange will tell if it can be and what needs to be done
You need to keep the gear ratio the same front and rear.
Good Luck