Pop the cap out with small screw diver Sam place as older units.you will see screw under that flat cap
I highly recommend signing up for the Toyota Forklift website ( https://shop.toyotaforklift.com/en/parts-group?model=8FGCU25&serial=C2248&assetNumber=) so you can view specific & exact part number's & pricing. Sign-up is free, and I use this website to price-match & find exact/specific parts. Are you looking for the LPG Regulator, or distributor, or if applicable, carburetor?
What is the model-serial?