What was original engine in 1983 Prout Snowgoose 37

[getyourbone]

Wondering if anyone might know what the original engine would have been in a 1983 Proit snowgoose 37 catamaran?

Currently has a Yanmar 3gm30f I believe? Would this have been the way it would have originally been spec’d? Was that model of engine even available then?

Reason for asking is because of registering it as an antique in Florida and that is one of the requirements.

Thanks,

Steve