Yambits has Fresco "Big One" exhaust pipes and silencers for monoshock DT125 and DT175 for sale, but they have listed the European versions DT125MX and list that they only fit the 1980-81 DT125MX and 1978-1981 DT175MX. My question is, aren't the pipes all the same for these bikes? A pipe that fits a 1980 DT125MX would fit a 1978 DT125E, correct? Are there differences between these two models that aren't made clear? I remember reading at some point that the side at which the pipe came out of the center of the frame flip flopped later in the years of the DT125 but I am not sure if that is correct. The parts numbers are SIL003 and SIL004.

For the DT125MX, Yambits only shows parts for the 80-81 years, period.  So that might mean they didn't get a DT125MX in 78 and 79... OR it's just a mistake?  (In other words, it's not just this pipe...  they don't show ANY parts for a 78-79 DT125MX)

Other members have bought the SIL004 pipe and it worked fine on a US bike...  I think one member in Canada had a 1978 he installed one on.

The Fresco SIL003 silencer could be problematic if you are in the US as it is unlikely to have a spark arrestor...  but fit should be fine.

As far as I know, the 78-81 DT175 and DT125 pipes and mufflers are all the same in the USA.