Mystery casting#

[Impalaguru]

I found some old tin foil casting number transfers from my old 64 SS and I found one I can't identify. I'm almost positive its a block casting# as it has a large GM next to it. The number is 3725899. There is a casting date right above it of J1662. Any ideas as to what this thing is?
Ross

[bignbad60]

belive you are looking at a Rear end Code

[Impalaguru]

:doh You're right! Its been so long since I took those numbers I forgot where they came from. Thanks!
Ross