I'd guess the cabinet is the same age as the machine. There are some siginficant differences between the later ones and the older ones. This one does not have a lift assist, and if there is no support bar for the flap, then it's likely this one is suppose to have the front door fully open to provide support for that flap (since you'd need it open to sew) so be careful having it open without the door to support it - the hinges can easily get sprung on these - or the screws start pulling out.
I think you've got a real nice machine and cabinet there!