just got a motor back number is 3970010 but i cant find the suffix code anywere its v0731TDS the 3970010 block can be a 302 327 or 350 just curious also on front of the motor under the suffix what does that number meen mine has a c8z21513 the z might b a 7 and there might be one more 3 after the other 3 get back asap need to konw bc im racing sat. if its a 350 thanks

Its a truck motor

v0731TDS
V - Flint Engine Plant (source)
07 - July
31 - Day engine made
TDS - Check this again, the S may be wrong. All truck engine suffix's begin with a T, passenger cars with a C. But all trucks were basically 350-165 HP

c8z21513 is the CON VIN derivative from the truck (legal identifier of the engine and these were stamped on the trans as well as body and frame of all vehicles from 1968 on, federal law)
C - Chevrolet truck division
8 - 1978 model year
Z - Fremont CA final assembly plant
21513? - Truck serial number (1 digit is missing)

3970010 is a common casting used for over 10 yrs by Chevrolet in every car, truck. The 302 use was very limited in late 1969 and very few Z28 came with the block as the 302 was being phased out, it dropped for 1970 models. The only reasons a few 0010 blocks ended up as 302 was because of the delay in the 1970 Camaro model. The 1969 was built late into Nov. of 69 and thus the 0010 was the only one in production by the engine plants and had to be use. No such thing as a "302 block" - it's the same block used for many other applications; the only thing that makes it a "302" is the crank, rods, pistons, cam, and heads assembled to it, and the suffix stamped on the pad later - there's nothing "special" about the block.