The way I understand it, the reason that the new ones don't have the heat provision is so that the same rear casting can be used on Chevy and GMC. There w=has been debate on which is better, water or exhaust for heat. I won't knock either way. I ran mine with no heat at all for some time, and performance was very good, but I am in the process of adding exhaust heat to mine, fabricating my own lines and plate. Did consider water heat, but didn't want to drill into my pump for water ports or remove the manifold to weld up the core plugs in it. I did test run with the plate and lines I made, it did improve it some, but right noe, I have to redo it as there is a gasket leak (that's what I get for making my own copper gasket) and a minir linkeage problem (sticking, same as gasket, that's what I get for fabbing y own
).
