If you mean Cookers, Portable, No.2 Mk 2 and No.3 Mk 3?
The EMER modifications & misc instructions:
Mods (control rod reservoir tank) issued January 1969
Mods (tank, cap, valve & feed tube) were issued in March 1974, superseded in June 1974.
Mods (burner assembly) in August 1982, superseded in Sept 1985
Mods (burner grid) July 1989
(EMER ENGINEERING & MISCELLANEOUS D 307 & D 309)