Well, that's not exactly true. PFI up here in Ft. Collins, Colorado (http://www.pfispeed.com) has put an H22 head onto an F23 block, but it isn't easy. You need lots of time, lots of money, lots of beer, and the willingness to go through all the headaches associated with the swap. For the most part, it's always more cost-effective just to transplant a DOHC engine.
Whoops... forgot about the F/H series crossover, as well as the F20C and K blocks... the F and H are still in the same family, for the most part- so it's not too bad. You can share transmissions, right?
Yeah, not too bad, but still not something that the everyday garage mechanic would want to undertake.
I'm under the impression that the trannies can be swapped with little or no problems. I know for a fact that clutch and flywheels are direct replacements. kaoskustoms lives here in Longmont with me, and he said he had a slight problem with swapping an F-series auto tranny onto an H23 block. Chad, can you shed some light on what happened?