When did they change the jacks from red/orange with the long support to black with the short support?

Bit of info here. viewtopic.php?t=91720
There is still debate on what was fitted and when. My own observations are that the black jack you have pictured was used for most of the mid 60's to late 70's including the Mk1 and Mk2 Cooper S.
The red one you have pictured has a longer support / engagement pin then the jacks i have used so it may be for very early or UK build cars. Or if you are really keen you could try and pick it out of the 100's of jacks listed here. http://www.classic-british-car-jacks.uk ... _index.htm