I guess I never really thought about it, I believe I read it was an hy35 and then in 2003 when the switch up to the CR stock was the hx35...I know I've heard alot of good things about em and I was wonderin what would be a good/my best option for upgrading my turbo...Can the hx be a direct swap?

HY35W is going to be the stock turbo for Automatic.HX35W is going to be the stock turbo for manuals.

Mike is correct but remember the early 24v auto's had hx35 too, maybe up to 2000. The 03 and early 04 trucks had an he341 that is about the same as your hy35 and the 04.5 till 07.5 had he351ce which is a popular upgrade for our 2nd gen trucks. Or the he351ve turbos from the 6.7 trucks with the built in exhaust brakes are nice but pricey with the controller.

So out of the HE351Ce or the hx35, whats going to be the best for me as far as housing size, possible pressure, and fitting if/when I swap...Or can my HY35(or a be sufficient enough to take the rig up to I guess the mid 400's hp and basically a medium duty towing with some street performance type truck? Or maybe even go aftermarket?

If you wanna do a cheap swap then go with just an hx, its a direct bolt on but an he351cw would be nice and have gotten folks close to 500hp. I have looked into swapping to a 351 myself and there are only a few changes you have to make to fit it up. I believe you will need a flang to fit it to the manifold, a down pipe, clock the housing and a pipe to go to the intercooler.

You could also go with the HX35/40 hybrid and it will bolt right up. Use that with RV 275s and you'll have a nice kick in the pants when you need to scoot!