Help decoding big truck vin and engine code

[backyardmechanic]

I have what I believe is a 1960 Chevy school bus. Trying to find out what the original engine was because it's missing and would like to find a replacement the same size. Any help would be appreciated. Thanks

Serial: 0S5302616139D
Engine : M516922

This is on the tag on the firewall

[tbucketnut]

Believe in 1960 6000 series trucks/buses could get a 261 cu inch inline loadmaster engine or a 348 cu inch v8 workmaster engine.

[jagarra]

In 1960 they also have a 283 listed so it's 261, 283 for the S60 series, it jumped to a 348 on the S70 series bus.

[backyardmechanic]

Thanks for the info. Just wondering how you decided it's 6000 series? How many ton is that? Is this determined by the S5302?

[jagarra]

I am using a "Motors Truck Repair " manual as a reference, 17th edison. In 1960 they list the motors for school buses, series S50-S70 the smallest motor is a S50 series with a 235, the rest have either a 261 or 283.
Maybe the motor mount position will let you have an idea of what was in there 6 or V8.

Your S503 could indicate a 50 series. Seating capacity could be a factor for bigger motors.
I have a 60-66 Chevy/GMC assembly manual and it has the vin information, but in your case I just could not find the vin info that matched.

[AZKen]

This is a GMC specific forum. With GMC enthusiasts and an expert knowledge base. You will be better served to go to a Chevy forum like Stovebolt.com