I googled 1974 Yamaha DT250A and clicked on Images - this should confirm or not whether it is a 74. I would think late '73 production would also lend itself to the right timeline for this.

Yes has low front guard with stripe . Thanks.  Now the search for parts start 

Yamaha VIN number absolutely says it's a 73.  The only question is what someone might have done to it in the last 50+ years.
72-73 were nearly identical...  71 and earlier models may have many of the same parts and/or parts that are "close enough".  So it's not unusual to see tanks swapped from different years, etc. 

Almost everything on a 72 is identical to your 73, except cosmetics like paint...  and your 73 should have a steering lock and most if not all 72's didn't. 

In contrast, 1974 was a complete redesign...  very different than 73.