My boat has a manual jet-o-vator currently installed on a 12JG. The previous owner also gave me a hydraulic Place Diverter. The jet-o-vator is really sloppy, so I'd like to put the diverter on. I kinda like the manual control. Can I do this swap with my current cables?

Gotta picture? really hard to say for sure, but I don't think so. 

GT

Assuming your rig still has the original 12jg split  bowl , the current Berk nozzle adaptor is rolled 90* to allow the up and down action of the JOV (pins at 3 and 9)  the Place unit trims after it steers so the Nozzle adaptor will need to be again turned 90* to put the pins at 6 and 12 to accerpt the P'Diverter ,you will need a standard Berk steer tube as the JOV steer tube  unit will not work ( is longer and not threaded the same designed to slide in and out thru a special bushing/seal arrangment ) and depending on the type manual controller  you will need almost certainly need a (43bc) different cable along with modifying the Hyd Place arm if you wish to have the PD be manual controlled Feel free to call if you need help   Tom

My trim control cable looks to be a 43bc even though it should have been a 43c. But it's probably too short to go through the transom. How long should the cable be in a Bahner 20ft Sportster?

Trim control cables for Place units are typically 43bc (except the LO Pro) Jet ovators can use a 43c or BC depending oln the controller Tom