identifying motor in my new truck

[Handy Andy]

So, I bought a new truck. Sold the old blue 86 k20 and picked up an 86 gmc sierra 1500. The new truck originally had a 305 in it, but the P.O. transplanted an older 350 into it. Only problem is, he doesn't know how much older... the number that is stamped into the boss on the front of the motor is "MG24400" and when I check that number on the net, I get pretty much nothing.... like as in the "MG" in the beginning of that number is not possible. I'm absolutely sure it says MG 24400, I've checked it a dozen times. Anyone got any suggestions? I guess it's not really absolutely imperative that I know the exact year, but it would be nice. I'm leaning towards it being a 78, but any info and help is greatly appreciated.

 

[RetroC10Sport]

Can you shoot a pic?

 

[Jrgunn5150]

I've only ever gotten casting number's from the rear of the block, behind the driver's side head, facing up.

 

[RetroC10Sport]

He's looking at the date and code stampings.

 

[Jrgunn5150]

I can never find them lol, they are always gone lol.

 

[bucket]

I've only ever gotten casting number's from the rear of the block, behind the driver's side head, facing up.

It can be hard to read while installed, but there's often a date code back there somewhere too.

 

[68post]

Is it possible that it's been rebuilt and decked - wiping out the factory stamping ? Then restamped by a rebuilder ?

 

[circuitguy]

Take a pic of the numbers at the rear top of the block and post them here, cant tell anything about it until we know these numbers.