Rich,
Thanks for the information. Maybe armed with them I will be able to resolve my dilemma.
For future reference of others, below are some pictures of my used rack alongside a metro rack.
Some numbers first:
Length of rack body from ege of pinion casting to flare of tube.
Marlin - 440 mm
Metro - 375 mm
Approx length of complete assembly from end of tie-rod to end of tie-rod
Marlin - 1130 mm
Metro - 1020 mm
Pinion shaft spline:
Marlin - 17t relatively coarse spline with one flat surface
Metro - 36t fine pitch spline with wasted centre complete circumference.
Marlin - 30 mm
Metro - 20 mm
Two racks together (Metro on right, Marlin on left)
Length of Metro rack from casting edge to flare.
Length of Marlin rack from casting edge to flare.
Metro spline:
Marlin spline:
