I'd definitely go with 1977 based on the single number. Most 60s O-I bottles I've found were still using the 2-digit code, and I believe they started dropping the two-digit again by the 70s. Based purely on the shape I'm thinking some kind of household cleaner - bleach, detergent, etc. Here's more reading on O-I if you're interested OP: https://glassbottlemarks.com/owens-illinois-glass-company/It looks like they changed the number on the mold which is why the 7 looks weird. They did that so that they could use the same mould for different years. It could also be 1977 since the 7 could mean either one.
Crass was a soda brand that operated from at least the 20s through the 70s or the 80s. I'm not 100% sure on the makers mark (assuming it's the L) - according to glassbottlemarks this could either be the Latchford Glass Company (though they didn't use a date code system) or the Laurens Glass Works, who did use two numbers to the side to give a date code.