[ConcussionHead]

So, I'm new to working on cars and I have a 4.3l vortec in an 01 sonoma 2wd. I've done all the work myself, learning in the process. I recently changed the lower intake manifold gasket and didn't properly align the distrubor when I put it back into the truck. So, my timing skipped. Lucky me. I assumed all I would need to do was set the engine to tdc and put the distrubor back in properly this time. Engine won't crank by hand, in which case I would have to assume it seized. I have been told by a few different people now that it sounds like the timing chain probably snapped. I was just wondering if this is what is most likely has happened or if there are other possibilities.

 

[Markv]

I don't understand the crank by hand thing, but I think that damper had two timing marks, and the chain cover has two points to line both marks up. You'll have to line up those marks on compression stroke and then drop in the dist.

 

[Cowboytrukr]

Turning it over with a breaker bar and socket = turn over by hand