It’s important to buy it from reputable place. Your seems legit but sometimes knock offs are sneaking up there too.
Im a huge fan of the Rat1 model, own few for myself. Seen few fake too. There is one that is marked Model 3, much larger that the original Rat 1.
‘Your looks fine, judging by the look of the scales, jumping, thumb studs and so on. Aus 8 Rats used to be made in Taiwan, excellent quality, I wasn’t fond of the initial HT but when they introduced the D2 models I was very happy.
One very good indication for authenticity of the early Rats is the D shape of the stand-off holes in the liners.
look at the below picture, youll se it. This is done because the standoffs and the stop pin are with the same shape and size so when your stop pin wears out with the time, you can replace it with one of the few available standoffs
Chinese copies do not have D shaped holes,t hey also use some clear super glue like for thread lock.
With the time, I think they got away from the D shape because I do have legitimate models that do not have the D holes.
Here few d measured parts, top is Chinese Rat 3, bottom Rat1
Here another old picture with few models along with the Ganzario ~ the Ganzo Rat with Axis lock.
Here are the lettering and part of the jumping
Your seems fine to me, I hope I’m not mistaking.