The engine is a d17. The ex has the d17a2 which has the vtec head. The dx, lx has the d17a1 which has the non-vtec head. I think the hx has the d17a2 with a little different work involved because of vtec-e. The bolting system on the head has changed. The displacement is different on the two engines as well as the electrical setup. The older d series has a return fuel system, while the new d17 series has the returnless fuel system.

Completely different engines.