Replacement through shaft and bearing carrier , shaft and endplates are stainless steel and the spacer is also stainless .
Shaft assembly comes delivered to you with the bearing carrier all in place , remove your original shaft and endplates , slide the new complete shaft into the outer hole nearest the wheel arch , there should be just enough to swing in around and slide in , push in until the new bearing carrier pushes up against the hole , then line carrier up so you can drill the 2 5mm holes , drill the holes then bolt up the bearing carrier with the shaft in place .
Then the other end of the shaft you can slide on the stainless steel spacer , bolt on the endplate with the spring hole towards the engine (Obvious i know but still better to say it and assume everyone will know ), making sure to line plate up with the 2 flats on the shaft , tighten nyloc nut up then hook up the spring as in the image . Then thats the new shaft fitted , if you find shaft dosent rotate freely this can be because the area where the bearing plate is bolted is not square to the chassis , you can tweek this area with adjustable spanner , after 40 odd years of abuse those plates take a pounding .
This shaft can be fitted from the wheel arch end, originally VW fitted these before fitting the brake master cylinder went in , so to replace from the inside of the chassis you would need to drop the master cylinder. But with this there is no need to .
One of the tips I have been given is its easier to hook the accelerator cable to the endplate before bolting onto the shaft as there is not much room up in there.