The Vortec comes with a 1 piece rear main which requires a high dollar flex plate, a special intake manifold if you're running a carb and the last one I installed didn't come with a harmonic balancer. I think the water pump was unique too, not for sure though. It was a good engine, just raised the cost up too much in my opinion. I put it in a mid 70's Vette, so I had a bad attitude to begin with on that job, LOL
Scott
