1973 Paragon P400 Transmission Seized

[Maurice]

1973 38' Hatteras - Starboard transmission seized at end of season last year. Now removed and getting rebuilt. Think it had been dragging for quite a while. Now I am wondering about the Port transmission. It indicates no problem, but at about 3000 hours should I expect the same problem? For most of the life of these engines and transmissions the average speed has been about 8-10 knots only in the fresh water of Georgian Bay. Engines are 427 ci rated at 300 hp. They run really smooth after 3000 hours.
Is there some way to "flush" these transmissions, and is it recommended? What would I use for flushing fluid? Thanks.

 

[UNIQUE_NAME]

there is no pan to drop so i think your only option is to suck it out of the filler cap.
even at that i dont know how much fluid you would get.
your best bet is to ask the rebuilding shop what they would recommend.

i would put new, longer, coolers in while you are there.
the originals were marginal at best and heat is the enemy.