The Talyllyn railway has four semi-open carriages, all three compartment four-wheelers. The first such vehicles were Nos. 7 and 8, acquired from the Penrhyn Quarry Railway in 1953. No. 7 was subsequently rebuilt as a tea-van and eventually into its current form (see below). Nos. 11, 12 and 13 entered service in 1955, 1956 and 1957 respectively and are somewhat larger and more substantially-built than the Penrhyn quarrymen’s carriages. No. 8 was renewed to a similar design in 1966. - Source:
https://www.talyllyn.co.uk/modern-carriages
The model simply requires a pair of Graham Farish spokes wheels, greenwhich or peco couplings and a roof.