Getting these measurements from a Rollerball - does that help?
Total length of nib and coupler (together) = 2.086"
Nib length incl. threaded plastic = 1.695", 43.12mm; excluding plastic = 1.441" or 36.62mm
Coupler insert to brass tube - diameter = 0.430", length 0.284" or 7.22mm
Coupler total length = 0.650", 16.51mm
Thread O.D. adjacent nib = 0.464" (11.74mm) (triple start, I believe) 1.0mm pitch
(cap to coupler); threaded length approx. = 0.243" or 6.17mm
Inner thread O.D. = 0.383" (9.77mm) 0.8mm pitch, threaded length = 0.263", 6.70mm
(nib to coupler)
Hope this helps; anything else ?
