i don't know where to look for the serial numbers on the engines. i had a look but could not find it.
But as i said, the engine models is called: D179 for the mcormick international 523 (3 cyl)and D206 for the mcormick international 624 (4 cyl) the make of year is between 1965 - 1972.
you see, i don't want to go and order exspensive work shop manuals just for this info. The manuals also just name them as a D179 and D206 International Havester engines.
i hope this info could help you.
I found the manuals for both tracktors and got all the info i need.
so , please cancel this request.
thank you very much for your effort
i will definitly make use of your services the next time when i gonna need some info.