MT-6 and MX-8 aren't the same action.
Lock up is different, mt had no drop out trigger, had coil springs, plus a couple other differences.
MX8 is the superior action by far, but the MT6 is still very serviceable. I have its trap single cousin the TM-1.
MT-6 came with both the striped and plain sided receiver and actually had approx. four generations of variants.