Block number decoding

[Gray Ghost]

I got these codes off the truck block in my C-20 and went to Mortec to decode....they have no numbers that match these and no link to anywhere that does. I would like to find out where this motor came from so I can decide better what to do if the block has issues when I get the thing torn down (like bad rings, etc.). For those who don't know, I had a head gasket go bad on me this week.

Here are the numbers....can anyone decode them? These were found at the front left of the block under the alternator bracket.

16R409392
TO905CMJ

Thanks, Kelly

[leastbay]

what kind of motor is it i know on my 350 the codes are by the firewall on the drivers side

[dons454s]

Could be a 350 or 305 according to my book you will need to get the back number off the block to be sure

[us111]

your gonna need the number's off of back of block like they said..there located on driver's side right at back of block..some are really hard to see,,i have heard of people using like play dough to put down in there and transfer number's,,,also have heard of using tin foil...you get these number's and they will point you where you need to go..good luck

[SanitysBane]

some times its really heard because off casting flast on the numbers too, its a real pita

[BIGCHEVYMAN]

this is a good site to find engine numbers. www.nastyz28.com

[Gray Ghost]

Thanks...I got it decoded...1974 350 4 bolt (could be police motor block) in a Caprice/Impala body style. I think I'll keep it....

The numbers off the back of the block don't tell ya much....3970014 = 2-4 bolt 350 70-76...not much info there.