Perez & Raimond Paris was a garage specializing in the reconditioning and dieselisation of trucks from military surplus from the Second World War.
In 1970, when Willème went bankrupt, they took over the exceptional tractor branch. To my knowledge, they did not use Mercedes engines, but only Detroit Diesels which they imported for France or, on request, Cummins.
Around 1978, PRP was no longer economically able to continue. The production of the Willème models came under the control of Irtex, a European group, which replaced the cabins with DAFs. Then in 1982, Mol bought the licenses and partially transformed the vehicles to make them an in-house product.