I'm having trouble determining the major differences between a 1973 MX250 and the same year DT3.  I'm not trying to determine each and every difference, but just big ticket items like frame and engine.

Are the frames essentially the same with the MX250 frame missing accommodations for battery, turn-signals, etc.?

And are the engines essentially the same (i.e., same engine cases) with the primary difference being the MX250's higher compression?

I'll post this then sort my mistakes.
That's a curly question that one, because i thought a true MX250 came out in "74 as did DT250 trail bike as opposed to DT3 "73 & DT2MX in think late "72.
All very confusing & i had both DT2MX new then MX250 new after that--but 50 odd years ago so my memory is fading as to exactly when each model arrived & might be late in one year--''new model for the next year''.
Ok then, DT3 & DT2MX have a lot in common & everything in both motors would interchange pretty much.
Then with MX250--"the next model" everything within reason would interchange with a DT250 "74.
Going back to DT2MX the frame would take a DT3 motor but is taller to allow for the pipe to cross over under the tank.
Also with MX250, those motors & DT250 would swap between frames.
Tell me more--sounds like a plan or project brewing?.

www.cmsnl.com/mx250_model16771/info/
www.yamaha-enduros.com/index.php/250cc-s...mx250-specifications

I was mostly wondering about differences between the MX250 motor and the DT1/2/3 motor.  Sounds like MX250 motor isn't backwards compatible?

Throttle grip should have an obvious difference--bigger hole but same size outside. Hope you didn't mistakenly end up with some for a Quad--ATV with same size both sides.