We never got a 1977 model CR250.
The 76 M2 was that far behind everything else, Honda never bothered bringing the 77 in, and waited out until the RZ arrived.
I bought a CR125M2 new in 1976, still have the receipt, it had the big muffler on it and it is on one of my M3s.
The muffler on this bike was purchased new from Elliot Bros Honda in Bendigo in 1995.