VF36 Twin Scroll, titanium turbine, large 47.9mm compressor as on 30/34/35 430cfm vf37 is same, not ball bearing
VF38 Twin Scroll, titanium turbine, smaller compressor
VF42 Twin Scroll, larger compressor than vf36, more efficient turbine. Similar in size to VF22
Don't know about the VF44 sorry