Transmission Identification

[Kisner]

Is there any way to possibly identify what type and year transmission I have in my 68 coupe without taking it apart. I know for sure it's a C-4 but the tag on the side is unreadable. Even after I scrubbed it with a steel wool pad you can't make out the #s or hardly any impressions the stamp made. I'm trying to figure out if it's the original or not - I suspect it's not since the original 289 was replaced with a 302 some years ago. Main reason I'm trying to find out is I want to replace the cheap, leaking $29 chrome pan with a good quality aluminum pan. However, every one I've found so far supposedly only fits 1970 or newer C-4s. The pictures of pan look identical to the one I have on it now so I'm not sure what changes were made in 1970. Thanks.