Hi all! Did a little searching but couldn’t find a decisive answer....I recently picked up a basket case ‘73 RT3 and a friend sold me a ‘74 DT360A engine. Obviously the top ends are different, so I wondered if the rest of motor is also different in other areas... I’m trying to keep this matching numbers and was curious if you can swap the crank from the later DT360A into a ‘73 RT3? Are they the same or different? Curious to know before I go tearing down a perfectly good engine for the crankshaft I may not need...

Would this be better placed in a different section of the forum? If so mods feel free to move...

I don't think it's the wrong section of the forum.  1974 was a complete redesign.  I don't have your answer but part numbers are completely different.  There's always a chance it might work but might be something you just have to try?  Not many people ever try to swap parts from obviously different engines.  One thing you could check fairly easy is the crank gear and gear splines...  I think you might find differences there?

I'm starting to dig into the 74 DT250... Its missing a muffler.. A gentleman in the for sale section, whom I contacted about this, said the 74 was a difficult bike to find parts for... It could be a one year and changes were made again..  I can't verify either way... but I am looking to find out..
Sneezles61

Ok, thanks guys! I think I’ll leave it be and just sell the complete engine in FS section here and see about finding the proper engine/bottom end for my bike 

From looking at pictures, the crank gear end is very different so I think you're making the right decision.