I have a 91 s10 with a sbc 355 in it. There’s no use on the factory wiring harness I’m using junction blocks. I have battery (yellow top optima battery ) in the truck bed. I have a high torque mini starter on the engine. When I go to start the truck I get 2 super slow cranks then it cuts out completely. I have 2 gauge ground running to the frame. A ground from frame to block. And ground from block to body. If I hook up jumper cables to my Silverado and put the other side of the cables ground to the block and positive to the starter post it will crank just fine and start up. Is there any other thing I could be missing that’s causing this? Any information will be great, thanks!