The TAC64 suppressor was the next evolution past the Model 63 suppressor.  What separated it from a TAC63 was that the TAC64 had ported 2 stage K baffles and not the M baffle with spacers.  The baffle improvement greatly reduced the first round pop and was much easier to clean.  It still had knurled endcaps for disassembly.  The endcaps were very difficult to remove once the can had been shot for awhile since there was no provision for a disassembly driving tool which is now standard on our current production TAC65 suppressors.  The TAC64 also had an OD dimension that was just enough to block the sights on the then newly released Walther P22.  The suppressor was only offered in gloss anodized black.

The TAC64 shown in the picture is a retrofitted model with updated baffles and endcaps.  You can easily tell the difference between the two by the presence of knurling on the end caps.  If they are knurled, they are the original older model.  If they are smooth with a blended radius, they are the newest retrofitted version.