A/C Heater box stamp number?

[Suregrip391]

Can anyone tell me what the correct number is supposed to be stamped on this 70 Satellite A/C heater box? I know the 177 is the day of the year in 1970, the number above it looks like it ends in a "3" ?

Anyone order a stamp online and know what size, border, font too? Thanks for the help.

 

[Pistol Pete]

Check here:

http://stores.ebay.com/SYLVAIN-STAM...?_fsub=2&_sid=111417603&_trksid=p4634.c0.m322

 

[Suregrip391]

Check here:

http://stores.ebay.com/SYLVAIN-STAM...?_fsub=2&_sid=111417603&_trksid=p4634.c0.m322

Thanks, I know of a few sellers for the stamps but wanted to know if anyone had a parts book to see what number should be on it. So I can get a stamp made locally. Some searches online say they can be had for around $10-$12