The Mk3 head is very similar but not the same as the Mk1, It can be modified (as well as the MGB) to accept the fold system. PP8 which is now in Hendon was used to demonstrate the loading capability of the EH101 in the C17, With a litttle work any EH101 will fit, either by folding the MRH or removing the MRB, the head stays put. From a modellers point of view the folding system is easy to model with the Mk1 parts as all the bits are within the head itself, no hydraulic lines etc