Mk1 cb-1 with canister rear shock

[Rexeriot]

Hi . I have a late mk1 which has the rear shock with the canister that mounts to a bracket on the left rear of the bike . I thought this rear shock set up was only in a mk2 but mines a mk1.  Anyone else got this set up ? I'm guessing they brought this mod I'm early. 

[Pod70]

I've had a couple of Mk1's with the canister shock, so I guess Honda switched the shock part way through production. It's a much better shock too