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#1 were you putting oil in the power steering pump or brake fluid in the master cylinder?
#2 sounds like a ignition switch issue i had on my 98,but i would check your starter before jumping to the ignition switch.Did you try to activate the starter by applying power to the small terminals on the starter it's self?
Good luck,with some more information you should be getting a few more responces
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews