Somerimes the serial number is hard to find — it would be unusual to not have one. Typically is engraved or stamped very small along the stern gunwale. At times on a sticker inside the cockpit.
What parts does it need? Many accessory pieces are generic — Topkayaker is an excellent resource for items like back bands, rudder hardware and even hatch covers.
Perception briefly made some thermoformed sea kayaks in their Airilite line including the Eclipse and Essence. The hatch covers on yours look like they may be replacements not OEM. Perception was kind of notorious for rapid turnover and annual changes to their many models. I have one of their composite outliers myself, only made for 2 years. The angled grab handle is an oddity, I admit.
Not surprised it turns out to be a BC made boat. That looks like a Feathercraft rudder — their kayaks were made from scratch in their shop on Granville Island in Vancouver and their rudders were so well regarded that some other companies used them for their models and they sold them separately for aftermarket retrofits (I’ve owned 4 FCs and still have 2 in the fleet.)
You should be able to retrofit a seat and backband into it. Sure looks like it was rode hard and put away wet! Could have been critter damage too. I bought a vintage kayak last year with rubber hatch covers that had been scalloped like a pie crust all around the entire rim by rodent teeth
Your post sent me down the rabbit hole – I’m always intrigued to know more about kayak brands and models that are new to me. I did find that there is a guy in Strathcona selling a different Extreme model – sending you the link because he includes closeups of the original seat. His looks older than yours – those hard plastic hatch covers went the way of the dinosaurs for most makers by the early 2000s. But since he says it was “custom”, with oversized hatches, they may have had to make the lids to conform to those odd shapes.
I found a number of old posts of unusual models from them – must have been an “artisanal” shop that specialized in custom builds. That reinforces that restoring yours would be a worthy project. Topkayaker.com could be a good resource – they have been helpful to me in the past in sourcing parts for vintage boats. I get replacement marine-grade bungee cord and salt-proof hardware from Sailrite.com.