Marks Hardware, 90 Series Mortise Lock 
Model: 90 Series: primarily used on ornamental steel security storm doors.
Standard Faceplate Measures: 1 x 7-1/8; 
Optional Faceplate measures 1-1/16 x 7-5/8 
Old style had a smaller faceplate- can usually be removed and re-installed on new box

Backset: 2-1/2 inch - From faceplate to center of handle
Square Handle Spindle: 1/4 inch Square 
The 1/4 square spindle is used with round knobs - Not levers 
There is a metal plate that prevents using a one piece spindle. This allows inside and outside handle to turn independent of each other and also enables the toggle on faceplate edge.

Handing: Right hand Reverse - Outswing door
Marks Locks are reversible, But better to order the correct handing.
See addtional images to determine handing
Double click on picture to enlarge
 

Lock Case, Marks Mortise, 90 Series LH / RHR - Choose Color

Related Marks Hardware:
301067 - Used with knobs, model 90 lock case, Left hand Reverse
301068 - Used with knobs, model 90 lock case, Right hand Reverse
301069 - Used with levers, model 9000 lock case, Right hand Reverse
301070 - Used with levers, model 9000 lock case, Right hand Reverse
The Marks 90000 Series Levers used a 5/16 square spindle

 

Resource:
How to Rehand Marks Mortise Locks