Check the link I provided. In all cases, the Si transmission has the more performance-oriented ratios, while the HF has the economy-minded ones.
I have read that the gearsets from the manual-transmission D-series cars will swap freely and easily around. The 5th gear from a later D-series is almost but not quite as tall as that from the HF, so it makes for a setup that is easier to find. The HF ones are more scarce than they used to be...
"Mista Bone" on several Honda BBSes (like
The CRX Community BBS) is a D-series transmission guru; he has built more of them than most of us have driven cars.
-soD