Need help on LM7 ID


New Member
Mar 20, 2014
1972 chevy c10 LWB
Hello everyone, I am getting ready to do a swap on my 1972 Chevy C10 LWB. I recently picked up a 5.3 liter engine and 4l60e thats mated, the wrecking yard says this came off a 2005 Chevy Tahoe and supposedly has only 58k miles on it, however the more research I do the more Im beginning to think otherwise but I am not 100% sure and really use someones help on the ID of this engine. block number I got that is behind the passenger side head is 12551358, there is a stamp on the front of the passenger side head on small deck on the block that reads F100 ? not sure if that means anything. I found these numbers on the heads themselves
G20207642865 the G might also be a 6 very hard to tell. hopefully someone can decipher these for me I would really appreciate it. I can try to find other numbers if someone can tell me where to look.

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