Hello I'm a new member and have a 96 suburban that sat for a while and when I started it it blew gas smoke for 10 minutes wdhen it stoopped smoking it had developed a knock. cked all the bearing and none of them were bad any ideas on what the knock is. Also I have a sub with a good 350, will that be a swap with a vortec motor. Alocal mech told me the gas prob. was an inline gas component that had ruptured inside the vortec manifold...would appreciate any help from all you savy chevy guys..............tks Troy