Got a motor don't know if its a 327 or 283 numbers GM 35 39700010 stamped on block tag # 639653 (1342)

The VIN Numbers are where you said. The engine has a casting number and a serial number that is not the VIN number, but is linked to the vehicle. Image a production line with 200 engines on pallets all numbered and waiting to go in a vehicle. The vehicle has a VIN number on it and they just pick the nearest engine and mount it, registering that number engine to the vehicle it went into.

14015445 Big Block V8 1978-1990 454, 2 bolt or 4 bolt

most likely a 250cid I-6. could be one of 4 varients available in base model gm cars and light trucks as well as UPS delivery trucks and Checker cabs. the LD4 was used in Cameros and Firebirds. the L22 was available in Chevy and GMC 1500 and suburbans.

I don't think you have anything that will help in your search.
The 95 Impala SS came with a 350 cu in engine stock. The VIN code was P and the horsepower rating was 260. The casting number for that block would be something like 10199001 or 14101148. After 1970 GM started stamping a partial vin number on the blocks to match the original car. If you had the original car you could check the 8th digit of the VIN to verify the engine.

You will have to find the casting number on the block, heads, and intake to see if all those are original to that motor, but the block casting number will tell you what year it was made, and the types of vehicles it was used in. It might be difficult to pinpoint exactly what it was in originally if they used it in more than one type car, or produced it more that one year. You can google up a site that will help you find the block casting and decode it for you. Just type in GM engine block decoder

it would have been helpful if the cars vin number was written on a tag attatched to this replacement motor..then you would have a better chance of an id..most blocks have a flat space on the edge of where the head bolts on that has a number stamped into it.. thats the block number you are looking for..

There has to be more to the stamped number...normally it is on the backside of the motor...but I am looking up that info you have provided.

Find the engine identification tag. Attached at the factory, this tag is normally found on the engine block around the coil bolts. The top line of the tag identifies engine size and model year.

Search the block for the engine block casting number. The numbers are raised, not stamped into the block and consist of seven numeric digits. The digits can be located on either side of the block. The seven-digit number may be followed with a dash and further numbers. These are change codes and are not normally necessary to identify the engine.

EX.:

Locate the casting date is located on the block. It is in standard date coding, 2.25.93, for example and may be located on either side of the block, but is commonly located on the driver's side of the block, above the freeze plugs. The example 2.25.93 decodes as February 25, 1993. The casting date may be near the casting clock, which designates the hour the block was cast. Magnum engines were manufactured from 1993 to 2002, so verifying the date code helps identify the engine.

site i use for casting numbers is down at the moment
far as if a camaro motor would work in your truck yes small blocks between trucks and cars the same
there are 2- bolt main blocks
and there are 4-bolt main blocks
2 and 4 bolts are used in cars
and 2 and 4 bolts are used in trucks
main differance between truck motors and car motors are the add ons intake exhaust manifolds
heads the blocks them self are the same
trucks are usally geared lower but that in the tranny and rear end not in the motor
soon as my site comes back up i look up your number for u and give u link to site as well

stamp= f 0412dbuilt in flint (mi)plant 0n april 12 an the casting number 3789935 from a chevy ll built in 1960-1961 its a 283 low horse power 170 high horsepower 220 and its a 2 bolt main have fun with it