if you look into the center of the block yu will or should see a head of a bolt, loosen this fully and you should be able to pull the bulkhead halfs apart... with any luck you may find rotted pins or pins that have gone green!
Yes your correct, I over read about having power to the junction block at the firewall, did you happen to separate the junction block at the fire wall then? if you have power on the engine side, then you should have power inside the cab at the junction block... I would suggest to separate the...
The original fusible leak used to come off of the starter solenoid main battery feed wire.... if blown it takes out power to everything. Not sure if you are working with original wiring or not ? It may of been cut out at onetime. Hope this may shed some light your way.