Twin disc 506 marine transmission low hours ratio is 2:93 to 1. Or. 3 to 1. .I have 2 transmission s from a boat that had twin motor s. 1 transmission has trolling valve 3300-$ each obo location is Canada central sannich near Sydney b c call for more info 250-885-9057 if add is up it's still for sale text or call for quick response