[HondaDustR]

The original "late" DME units used a 24 pin ROM chip that contains the fuel and ignition timing maps, and the basic programming binaries that told the CPU how to run the thing were stored inside a small bit of memory contained within the CPU itself. Later "late" DME's (around 87/88) went to a larger capacity 28 pin ROM chip that merely consolidated the CPU program code and the fuel/ignition maps onto the socketed ROM chip. The interesting thing is, the CPU chip was left unchanged and just had a jumper set on the circuit board to instruct it to ignore its on-chip code and use the code on the ROM, which is identical. You can still use a 24 pin ROM chip in a 28 pin DME by cutting the jumper.

The late 944 NA's got a slight cam upgrade, with the exhaust cams having 1mm more lift than the early cams. The early cam and the turbo cam are both identical, and a late cam is an easy minor upgrade for an early NA or a turbo.

The 944 shares lots of parts with other Porsches, and even VW's and Audi's. The valve stem seals are also 911 parts, the cam tower screw plugs are also oil pan drain plugs for Boxsters (and cost $17 each!), the early ignition switch is the same as early VW Beetles and can be had for a fraction of what Porsche charges, and the CV joints are also Audi equivalents (can't remember which one).

Upper radiator hoses might actually fail on 944's more often because they get rubbed by the alternator pulley than by just going bad. Often it's because the radiator isn't correctly mounted, the rubber mounts have gone bad, the sheet metal the mounts sit in are bent from running off the road/running over something big, or the hose is installed backwards.